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DCTC 2018 QUINTA EDIZIONE
Quinto Congresso della Divisione di Chimica Teorica e Computazionale
della Societagrave Chimica Italiana
Universitagrave degli Studi di Trieste 19 - 21 settembre 2018
aula 1A Edificio H3 Via Alfonso Valerio 122
dctc18unitsit
Comitato scientifico
Vincenzo Barone
Carlo Adamo
Benedetta Mennucci
Maria Cristina Menziani
Michele Pavone
Nino Polimeno
Cristina Puzzarini
Emilia Sicilia
Mauro Stener
Comitato organizzatore locale
Mauro Stener
Giovanna Fronzoni
Daniele Toffoli
PROGRAMMA
Mercoledigrave 19 Settembre 1445-1500 Apertura del congresso
Sessione 1 Chairman Maria Cristina Menziani
1500-1545 Invited ndash Piero Decleva
Solving the Schroumldinger equation in a box wavepackets and continuum states
1545-1600 Sofia Canola ldquoVibrational and optical fingerprints of conjugated
biradicals from DFT and TDDFT calculationsrdquo
1600-1615 Marco Mendolicchio ldquoNew computational strategies for the calculation of
anharmonic force fieldsrdquo
1615-1630 Loredana Edith Daga ldquoOn Optimizing Gaussian Basis sets for Crystalline Solidsrdquo
1630-1700 Coffee Break (Atrio edificio H3)
Sessione 2 Chairman Benedetta Mennucci
1700-1745 Invited ndashFabrizio Santoro
Mixed quantumclassical description of the effects of nuclear motion in electronic
spectroscopy and ultrafast photophysics
1745-1800 Emanuele Coccia ldquoWave function-based approach to probe coherence in ultrafast
molecular processesrdquo
1800-1815 Amalia Velardo ldquoBand Shapes of Singlet-Triplet Transitionsrdquo
1815-1830 Laura Zanetti Polzi ldquoModeling amide I infrared spectra of proteins insights from
a perturbative approachrdquo
Giovedigrave 20 Settembre Sessione 3 Chairman Carlo Adamo
915-1000 Invited ndash Ana B Muntildeoz Garciacutea
Defective but effective the role of defects on the electrocatalytic performance of
oxide-based materials for energy conversion
1000-1015 Mario Prejanograve ldquoThe effect of distortions of a covalent enzymatic intermediate in
Human Transketolase a computational point of viewrdquo
1015-1030 Francesco Sessa ldquoLa3+
ion in EAN aqueous mixtures a MD-XAS investigation on
the effect of water concentrationrdquo
1030-1045 Diego Cesario ldquoSource of Cooperativity in Hydrogen-Bonded Supramolecular
Polymersrdquo
1045-1130 Coffee Break (Terrazza aula 1B primo piano edificio H3)
Sessione 4 Chairman Nino Polimeno
1130-1215 Invited ndashAnna Painelli
Solvent dynamics and energy transfer a real time description
1215-1230 Gloria Mazzone ldquoAiming at Color Prediction of Flexible Dyes in Aqueous
Solution Combined Molecular Dynamic and Quantum Mechanic approachesrdquo
1230-1245 Michele Guerrini ldquoSolid-state effects on the optical excitation of push-pull
molecular J-aggregates by first principles simulationsrdquo
1245-1300 Mirco Zerbetto ldquoPrevisione dei Tempi di Rilassamento NMR di Molecole
Flessibili Oligosaccaridi come Caso di Studiordquo
1300-1530 Pranzo + Poster session (Atrio edificio H3)
Sessione 5 Chairman Cristina Puzzarini
1530-1545 Francesco Faglioni ldquoSelf interaction charge delocalization electrolyte
ionizationrdquo
1545-1600 Mattia Anzola ldquoOptical spectra of molecular aggregates testing approximation
schemesrdquo
1600-1615 Martina De Vetta ldquoSimulations of a liposomal assisted delivery of the Temoporfin
photosensitizerrdquo
1615-1630 Matteo Masetti ldquoThe best of both worlds combining Markov State Models and
Path Collective Variables to describe protein-ligand bindingrdquo
1630-1645 Ida Ritacco ldquoThe mechanism of post-translation regulation of estrogen
biosynthesis in Breast cancer cells as revealed by atomic level multiscale
simulationsrdquo
1645-1700 Tommaso Giovannini ldquoDevelopment of Theoretical Approaches to Model the
Spectral Properties of Complex Systemsrdquo
1700-1745 Invited ndash Marco Garavelli
Towards an accurate computational photochemistry and photobiology the
paradigmatic case of vision
1745-1900 Assemblea della Divisione di Chimica Teorica e Computazionale della SCI
Venerdigrave 21 Settembre Sessione 6 Chairman Emilia Sicilia
915-1000 Invited ndash Gianni Cardini
Modellizzazione in fase condensata ad alte pressioni
1000-1015 Fortuna Ponte ldquoComputational investigation of the platinum(IV) anticancer
prodrugs reduction mechanism by L-ascorbic acidrdquo
1015-1030 Laura Falivene ldquoTuning Proximal and Remote Steric Effects in the
Rationalization of Catalytic Behaviorrdquo
1030-1045 Eduardo Schiavo ldquoInvestigating photoelectrochemical properties of dye-electrode
interfaces with density functional embedding theoryrdquo
1045-1100 Tainah Dorina Marforio ldquoCarbon nanotubes (CNTS) as nano-reactors
regioselectivity and kinetics control for the bromination of N-phenylacetamide A
QMMM investigationrdquo
1100-1145 Coffee Break (Atrio edificio H3)
Sessione 7 Sessione premi e medaglie Nordio ndash del Re ndash Scrocco ndash Roetti
Chairman Vincenzo Barone
1145-1200 Premio del Re Francesco Avanzini ldquoThe Quantum Molecular Trajectoryrdquo
1200-1230 Premio Scrocco Francesco Muniz-Miranda
Studies on the optoelectronic properties of metal nanoclusters and complexes
1230-1300 Premio Roetti Lorenzo Maschio
Quantum chemistry of crystalline solids using a local basis set the CRYSTAL
and CRYSCOR codes
1300 Conclusioni
Conferenze su invito Nome DipartimentoIstituzione Titolo contributo n
Piero Decleva DSCF Universitagrave di Trieste
Solving the Schroumldinger equation in a box wavepackets
and continuum states
I1
Fabrizio Santoro
ICCOM-CNR Area della Ricerca
del CNR di Pisa
Mixed quantumclassical description of the effects of
nuclear motion in electronic spectroscopy and ultrafast
photophysics
I2
Ana B Muntildeoz
Garciacutea
Dipartimento di Fisica ldquoEttore
Pancinirdquo Universitagrave di Napoli
Federico II
Defective but effective the role of defects on the
electrocatalytic performance of oxide-based materials for
energy conversion
I3
Anna Painelli
Dipartimento SCVSA Universitagrave
di Parma
Solvent dynamics and energy transfer
a real time description
I4
Marco Garavelli
Dipartimento di Chimica
Industriale ldquoToso Montanarirdquo
Bologna
Towards an accurate computational photochemistry and
photobiology the paradigmatic case of vision
I5
Gianni Cardini
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave di Firenze
Modellizzazione in fase condensata ad alte pressioni I6
Premi
Nome DipartimentoIstituzione Titolo contributo premio
Lorenzo Maschio Dipartimento di Chimica
Universitagrave di Torino
Quantum chemistry of crystalline solids using a local
basis set the CRYSTAL and CRYSCOR codes
Roetti
Francesco Muniz-
Miranda
Gent Universiteit Belgieuml Studies on the optoelectronic properties of metal
nanoclusters and complexes
Scrocco
Francesco Avanzini Dipartimento di Scienze
Chimiche Universitagrave degli Studi
di Padova
The Quantum Molecular Trajectory del Re
Contributi Orali
Nome DipartimentoIstituzione Titolo contributo n
Sofia Canola
Dipartimento di Chimica ldquoG
Ciamicianrdquo University of
Bologna via F Selmi 2 Bologna
Italy
Vibrational and optical fingerprints of conjugated
biradicals from DFT and TDDFT calculations
O1
Marco
Mendolicchio
Scuola Normale Superiore I-
56126 Pisa Italy
New computational strategies for the calculation of
anharmonic force fields
O2
Loredana Edith
Daga
Diparimento di Chimica
Universitagrave di Torino
On Optimizing Gaussian Basis sets for Crystalline Solids O3
Emanuele Coccia
Dipartimento di Scienze
Chimiche Universitagrave di Padova
via Marzolo 1 Padova Italy
Wave function-based approach to probe coherence in
ultrafast molecular processes
O4
Amalia Velardo
Dipartimento Chimica e Biologia
ldquoAdolfo Zambellirdquo Universitagrave
degli Studi di Salerno Via G
Paolo II 84084-Fisciano Italy
Band Shapes of Singlet-Triplet Transitions
O5
Laura Zanetti-Polzi
Department of Physical and
Chemical Sciences University of
LAquila Via Vetoio (Coppito1)
67010 LAquila Italy
Modeling amide I infrared spectra of proteins insights
from a perturbative approach
O6
Mario Prejanograve
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende (CS) Italia
The effect of distortions of a covalent enzymatic
intermediate in Human Transketolase a computational
point of view
O7
F Sessa
Department of Chemistry
University of Rome ldquoLa
Sapienzardquo Rome Italy
La3+ ion in EAN aqueous mixtures a MD-XAS
investigation on the effect of water concentration
O8
Diego Cesario
- Department of Chemistry and
Pharmaceutical Sciences and
Amsterdam Center for Multiscale
Modeling Vrije Universiteit
Amsterdam De Boelelaan 1083
1081 HV Amsterdam The
Netherlands
- Department of Chemistry
Biology and Biotechnology
University of Perugia
via Elce di Sotto 8 I-06123
Perugia Italy
Source of Cooperativity in Hydrogen-Bonded
Supramolecular Polymers
O9
Gloria Mazzone Chimie ParisTech PSL Research
University CNRS Institut de
Recherche de Chimie Paris Paris
France
Aiming at Color Prediction of Flexible Dyes in Aqueous
Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
O10
Michele Guerrini
Dipartimento FIM Universitagrave di
Modena e Reggio Emilia Italy
Solid-state effects on the optical excitation of push-pull
molecular J-aggregates by first principles simulations
O11
Mirco Zerbetto
Dipartimento di Scienze
Chimiche Universitagrave degli Studi
di Padova Padova 35313 Italia
Previsione dei Tempi di Rilassamento NMR di Molecole
Flessibili Oligosaccaridi come Caso di Studio
O12
F Faglioni
DSCG Univ of Modena and
Reggio Emilia Modena Italy
Self interaction charge delocalization electrolyte
ionization
O13
Mattia Anzola
Dipartimento di Scienze
Chimiche della Vita e della
Sostenibilitagrave Ambientale
Universitagrave degli Studi di Parma
Italy
Optical spectra of molecular aggregates testing
approximation schemes
O14
Martina De Vetta
-Institute of Theoretical
Chemistry Faculty of Chemistry
University of Vienna Waumlhringer
Str 17 A-1090 Vienna Austria
-Departamento de u mica
Universidad Aut noma de Madrid
Francisco Tomaacutes y Valiente 7
28049 Cantoblanco Madrid Spain
Simulations of a liposomal assisted delivery of the
Temoporfin photosensitizer
O15
Matteo Masetti Department of Pharmacy and
Biotechnology (FaBiT) Alma
Mater Studiorum ndash University of
Bologna Italy
The best of both worlds combining Markov State Models
and Path Collective Variables to describe protein-ligand
binding
O16
Ida Ritacco
CNR-IOM co SISSA via
Bonomea 265 34136 Trieste Italy
The mechanism of post-translation regulation of estrogen
biosynthesis in Breast cancer cells as revealed by atomic
level multiscale simulations
O17
Tommaso
Giovannini
Scuola Normale Superiore Piazza
dei Cavalieri 7 Pisa IT
Development of Theoretical Approaches to Model the
Spectral Properties of Complex Systems
O18
Fortuna Ponte
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria
Computational investigation of the platinum(IV)
anticancer prodrugs reduction mechanism by L-ascorbic
acid
O19
Laura Falivene
KAUST Catalysis Center King
Abdullah University of Science
and Technology Thuwal 23955-
6900 Saudi Arabia
Tuning Proximal and Remote Steric Effects in the
Rationalization of Catalytic Behavior
O20
E Schiavo
Department of Chemical Sciences
University of Naples Federico II
Comp Univ Monte SantrsquoAngelo
Via Cintia 21 80126 Naples Italy
Investigating photoelectrochemical properties of dye-
electrode interfaces with density functional embedding
theory
O21
Tainah Dorina
Marforio
Dipartimento di Chimica ldquoG
Ciamicianrdquo Alma Mater
Studiorum ndash Universitagrave di
Bologna via Selmi 2 40126
Bologna
Italy
CARBON NANOTUBES (CNTS) AS NANO-
REACTORS
REGIOSELECTIVITY AND KINETICS CONTROL
FOR
THE BROMINATION OF N-PHENYLACETAMIDE
A QMMM INVESTIGATION
O22
Poster Nome DipartimentoIstituzione Titolo contributo n
F Cappelluti
Universitagrave degli Studi dellrsquoAquila
- LrsquoAquila
F-RESP a fast and accurate polarizable force field P1
Francesco Tavanti
Department of Chemical and
Geological Sciences University of
Modena and Reggio Emilia Via
Campi 103 41125
Modena Italy
Natural compounds for Alzheimerrsquos disease treatment a
classical
Molecular Dynamics investigation
P2
E Bernes
Department of Chemical and
Pharmaceutical Sciences
University of Trieste 34127
Trieste Italy
Core-Electron Excitations in Dibenzothiophene
Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
P3
Baiano C
Department of Chemical Sciences
University of Naples Federico II
Ab initio characterization of CO2 photoreduction
mechanism at CuFeO2 delafossite electrode
P4
Davide Accomasso
Department of Chemistry and
Industrial Chemistry University
of Pisa Italy
Seeking new materials for singlet fission
covalent dimers as an alternative to molecular crystals
P5
Henry Adenusi
Chemistry Department University
of Rome ldquoLa Sapienzardquo Italy
Proton transfer mechanisms in protic ionic liquids P6
Giorgia Beata
Dipartimento di Chimica
Universitagrave di Torino Via Giuria 7
I-10125 Torino Italy
CRYSPLOT a new tool to visualize physical and
chemical properties of crystalline solids
P7
Marco Pagliai
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave degli Studi di
Firenze via della Lastruccia 3
50019 Sesto Fiorentino (FI) Italy
Molecular dynamics simulations of zinc proteins a
new force field
P8
Eslam M Moustafa
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria I-87036 Aracavacta
di Rende (CS) Italy
Reduction of Pt(IV) anticancer drugs a DFT mechanistic
study
P9
Alessandro Landi
Dipartimento di Chimica e
Biologia Adolfo Zambelli
Universitagrave di Salerno Via
Giovanni Paolo II I-84084
Fisciano (SA) Italy
Rapid evaluation of dynamic disorder in organic
semiconductors
P10
Isabella Romeo
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende I-87036
Italy
De novo proteins Insights from the theoretical
investigations
P11
Marina
Macchiagodena
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave degli Studi di
Firenze Via della Lastruccia 3 I-
50019 Sesto Fiorentino Italy
Improved force fields for molecular dynamics
simulations of zinc proteins
P12
Marco Fusegrave
Scuola Normale Superiore Piazza
dei Cavalieri 7 56126 Pisa Italy
Computational simulation of vibrationally resolved
spectra for spin‐forbidden transitionsforbidden transitions
P13
Tiziana Marino
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende I-87036
Italy
De novo proteins Insights from the theoretical
investigations
P14
Matteo Capone
Universitagrave dellrsquoAquila Italia Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
P15
J FREGONI
Dipartimento di scienze Fisiche
Informatiche e Matematiche
University of Modena and Reggio
Emilia I-41125 Modena Italy
Manipulating azobenzene photoisomerization
through strong light-molecule coupling
P16
Irene Conti
Dipartimento di Chimica
Industriale ldquo Toso Montanarirdquo
Universita di Bologna Viale del
Risorgimento 4 I-40136 Bologna
Italy
Excitonic State evolution of DNA Stacked Thymines
Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
P17
Andrea Le Donne
Chemistry department University
of Rome ldquoLa Sapienzardquo Rome
Italy
Ionic Liquids and Proton Transfer A Computational
Study to Understand Dynamic Processes
P18
Franco Egidi
Scuola Normale Superiore 56126
Pisa Italy
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
P19
Arianna Massaro
Department of Chemical Science
University of Naples ldquoFederico
IIrdquo via Cintia 21 80126 Naples
Italy
Unveiling the role of structural features in Na insertion
mechanism at anatase surfaces new insights for Na-ion
batteries development
P20
Alessandro Landi
Dipartimento di Chimica e
Biologia Adolfo Zambelli
Universitagrave di Salerno Via
Giovanni Paolo II I-84084
Fisciano (SA) Italy
Hole Mobility in Organic Semiconductors A Second-
Order Cumulant Approach
P21
Mariagrazia Fortino
Universitagrave di Modena e Reggio
Emilia Modena 41125 Italy
On the Simulation of Vibrationally Resolved Electronic
Spectra of medium-size molecules the case of Styryl
Substituted BODIPYs
P22
Marco Medves Dipdi Scienze Chimiche e
Farmaceutiche Universitagrave di
Trieste
Theoretical Study on the Circular Dichroism of Chiral
Bimetallic Clusters Ag-Au
P23
Jonathan Campeggio
Universitagrave degli Studi di Padova DiTe2 Calcolo del tensore di diffusione per molecole
flessibili
P24
Edoardo Jun
Mattioli
Chemistry Department ldquoG
Ciamicianrdquo University of Bologna
Computational Investigation of Competitive
Reaction Mechanisms inside Carbon Nanotubes
P25
Sergio Rampino
SMART Laboratory Scuola
Normale Superiore Piazza dei
Cavalieri 7 56126 Pisa
Combined Orbital-spaceReal-space Analysis of
Chemical Bonding through Virtual Reality
P26
Josephine Alba Dipdi Chimica Universitagrave di
Roma La Sapienza
Efficient and Accurate Modelling of Conformational
Transitions in proteins comparison between two Src
kinase proteins
P27
Abstracts delle conferenze su invito
I1
Solving the Schroumldinger equation in a box wavepackets and continuum states
Piero Decleva
DSCF Universitarsquo di Trieste declevaunitsit
ABSTRACT
Nelle molecole gli stati elettronici piursquo bassi decadono esponenzialmente con unrsquoestensione spaziale molto limitata Questo non ersquo piursquo vero per
- Stati Rydberg con alti numeri quantici - Stati del continuo - Pacchetti generati da impulsi elettromagnetici molto intensi
In tal caso le basi LCAO costruite da GTO o STO risultano inadeguate e sono necessari approcci alternativi sia funzioni di base diverse sia uso di griglie numeriche Per lo studio del continuo elettronico abbiamo da tempo sviluppato un set basato sullrsquouso di B-spline [1] come funzioni radiali adoperate nel modo LCAO convenzionale che si ersquo dimostrato assai flessibile e accurato Queste forniscono unrsquoeccellente rappresentazione delle soluzioni dellrsquoequazione di Schroumldinger allrsquointerno di una sfera di raggio prefissato arbitrario Calcoli dei parametri di fotoionizzazione molecolare a livello DFT [2] o TDDFT [3] forniscono generalmente risultati in buon accordo con lrsquoesperimento anche per sistemi relativamente grandi e per un gran numero di osservabili di fotoionizzazione sezioni drsquourto distribuzioni angolari di molecole con orientazione fissa o casuale parametri non-dipolari effetti di interferenza e diffrazione parametri chirali Ersquo stata anche applicata a fotoionizzazione risolta nel tempo da stati eccitati in esperimenti pump-probe e alla generazione di pacchetti di cationi da impulsi ultraveloci Piursquo recentemente la base ersquo stata applicata al calcolo di pacchetti drsquoonda eccitati da impulsi laser in regime non perturbativo Durante lrsquoimpulso lrsquoescursione dellrsquoelettrone puorsquo raggiungere migliaia di unitarsquo atomiche ma lrsquoapproccio ersquo numericamente molto stabile e si presta bene all propagazione del pacchetto per risoluzione dellrsquoequazione temporale Ersquo stata considerata la ionizzazione totale in funzione dellrsquoorientazione del campo rispetto alla molecola [4] il calcolo dello spettro di elettroni risolto in energia ed angolo attraverso la proiezione sugli autostati del continuo la rivelazione di pacchetti elettronici coerenti in esperimenti pump-probe agli attosecondi [5] la generazione di armoniche alte (HHG) [6] Verranno illustrati alcuni risultati recenti e discusse le linee di sviluppo
REFERENCES
1 H Bachau E Cormier P Decleva J E Hansen and F Martin ldquoApplications of B-splines in Atomic and Molecular Physicsrdquo
Reports on Progress in Physics 64 1815 (2001)
2 D Toffoli M Stener G Fronzoni and P Decleva ldquoConvergenge of the Multicenter B-spline DFT approach for the continuumrdquo
Chem Phys 276 25 (2002)
3 M Stener G Fronzoni and P Decleva ldquoTime-dependent density-functional theory for molecular photoionization with
noniterative algorithm and multicenter B-spline basis set CS2 and C6H6 case studiesrdquoJ Chem Phys 122 (2005) 234301
4 S Petretti YV Vanne A Saenz A Castro and P Decleva ldquoAlignment-Dependent Ionization of N2 O2 and CO2 in Intense
Laser Fieldsrdquo Phys Rev Letters 104 (2010) 223001
5 M Ruberti P Decleva and V Averbukh ldquoMulti-channel dynamics and correlation-driven inter-channel couplings in high
harmonic generation spectra of aligned CO2 molecule ab initio Time Dependent B-spline ADC ab initio analysisrdquo Phys Chem
Chem Phys 20 (2018) 8311
6 E Plesiat M Lara-Astiaso P Decleva A Palacios and F Martin ldquoReal-time determination of ultrafast charge dynamics in
tetrafluoromethane from attosecond pump-probe photoelectron spectroscopyrdquo Chem Eur J 242018 xxx
I2
Mixed quantumclassical description of the effects of nuclear motion in electronic spectroscopy and ultrafast
photophysics
Fabrizio Santoro1
1 ICCOM-CNR Area della Ricerca del CNR di Pisa Italy 2 Affiliazione 2
fabriziosantoroiccomcnrit
ABSTRACT
Quantum nuclear effects can play a relevant role in determining the shape of electronic spectra and the fate of the photoexcited dynamics in molecular systems Recent advancements in fully quantum vibronic approaches for the computation of spectra [12] and in quantum-dynamical (QD) approaches like those provided by the MCTDH method [3-5] allow an efficient description of such effects even in large systems if they are rigid (harmonic) and in gas phase Flexible systems or systems embedded in solvents or in heterogenoeus media possibly establishing with them specific interactions represent a challenge for fully quantum treatments of nuclear motions Classical and semi-classical trajectory based approaches are very well suited to deal with these cases but they neglect quantum nuclear effects We believe that the development of wise mixed quantum classical (MQC) approaches may represent a suitable framework to overcome some of these present limitations In this contribution we present our recent work in this field In electronic spectroscopy we introduced mixed schemes that separate fast and slow degrees of freedom (DoF) on the grounds of an adiabatic approximation and treat the fast DoF at quantum level and the slow ones (including the solvent) at classical level The spectra are then naturally expressed as an average of vibronic spectra involving along the fast DoF over the distribution of the classical DoF [5-7] Extending these ideas to ultrafast photophysical processes we recently proposed a MQC approach to introduce environmental dynamical effects in QD simulations In its simplest version all the solute degrees of freedom are represented by a wavepacket moving according to nonadiabatic quantum dynamics while the motion of an explicit solvent model is described by an ensemble of classical trajectories The core idea of the method is to describe the mutual coupling of the solute and solvent dynamics within a mean-field framework In this way the Hamiltonians of both the quantum and classical subsystems contain time-dependent terms due to the interaction with the other subset and the quantum and classical equations of motions are solved simultaneously We will discuss the potentialities limitations and possible perspectives of these methods with a number of test applications
REFERENCES
1 Barone V WIREs Comput Mol Sci 2016 6 86-110 2 Santoro F Jacquemin D WIREs Comput Mol Sci 2016 6 460-486 3 Wang H Thoss M J Chem Phys 2003 119 1289minus1299 Vendrell O Meyer H-D J Chem Phys 2011 134 044135 4 Beck M H J ckle A Worth G A Meyer H-D Phys Rep 2000 324 1minus105 5 CerezoJ Avila F Prampolini G Santoro F J Chem Theory Comput 2015 11 5810ndash5825
6 Cerezo J Mazzeo G Longhi G Abbate S Santoro F J Phys Chem Lett 2016 7 4891‐4897 7 Cerezo J Aranda D Avila F Mazzeo G Longhi G Abbate S Santoro F Chirality 2018 30 730ndash743 8 Cerezo J Liu Y Lin N Zhao X Improta R Santoro F J Chem Theory Comput 201814 820ndash832
I3
Defective but effective the role of defects on the electrocatalytic performance of oxide-based materials
for energy conversion
Ana B Muntildeoz Garciacutea1
1 Dipartimento di Fisica ldquoEttore Pancinirdquo Universitagrave di Napoli Federico II
Comp Univ Monte S Angelo via Cintia 21 80126 Napoli (Italia)
anabelenmunozgarciauninait
ABSTRACT
Ab initio simulations play an increasingly important role in materials sciences In the energy conversion scenario computational modeling can elucidate with atomic resolution the subtle composition-structure-property relationships behind the performance of functional materials and complex interfaces In heterogeneous electrocatalysis the underlying bulk and surface chargemass transport events are often strongly dependent on the presenceabsence of structural defects Thus a deep knowledge of defect chemistry is key for understanding tuning and optimizing the properties of different catalysts In particular this contribution will report recent advances in the DFT-based characterization of the role of defects in strongly correlated oxides as electrodes in electrocatalytic devices Three case studies will be presented (i) a new triple-conducting oxide based on Sr2Fe15Mo05O6 perovskite with promising bifunctional catalytic activity towards oxygen reduction and evolution reactions [1-3] (ii) Fe-doped ZrO2 for low temperature PEMFCs [4] and (iii) CuFeO2 delafossite for CO2 photoreduction [5] In all these cases we will discuss how surface oxygen vacancies -boosted by aliovalent doping- can improve the electrode performance and change product selectivity In conclusion this contribution will highlight the merits of computationally driven materials discovery in the context of energy conversion devices pointing out the importance of the necessary interplay between theory and experiment
REFERENCES
1 ABMG D Bugaris M Pavone J P Hodges A Huq F Chen H-C zur Loye E A Carter J Am Chem Soc 134 6826 (2012) 2 ABMG M Pavone Chem Mater 28 490 (2016) 3 ABMG M Pavone J Mater Chem A 5 12735 (2017) 4 P Madkikar D Menga G Harzer T Mittermeier A Siebel F E Wagner M Merz S Schuppler P Nagel ABMG M Pavone H A Gasteiger M Piana Submitted 5 J Gu A Wuttig J W Krizan Y Hu Z M Detweller R J Cava A B Bocarsly J Phys Chem C 117 12415 (2013)
I4
Solvent dynamics and energy transfer a real time description
Anna Painelli Francesco Di Maiolo
Dipartimento SCVSA Universitagrave di Parma annapainelliuniprit
ABSTRACT
Energy dissipation and relaxation phenomena are crucial to describe the dynamics of excited states The interaction of a molecule with the environment (the bath) is pivotal in this respect bringing theoretical chemistry towards the field of open quantum systems Several strategies are available to quantitatively describe the system-bath interaction most often based on the dynamics of the reduced density matrix Vibrational degrees of freedom must be explicitly described to address internal conversion and the huge dimension of the resulting basis imposes dramatic approximations to the calculation Here we face the problem adopting an essential state model (ESM) description of the molecular systems ESMs proved successful in describing low-energy linear and non-linear optical spectra of several families of organic dyes in terms of a minimal number of electronic states coupled to few effective vibrational modes ESMs successfully account for polar solvation and for intermolecular interactions in molecular aggregates and in energy transfer systems (1 2 3)
Here we present a dynamical non-adiabatic model for Resonance Energy Transfer (RET) Specifically we consider two dyes an energy donor (D) and an energy acceptor (A) Each dye corresponds to a push-pull chromophore described in terms of two electronic states coupled to a single effective vibration Accounting for dissipation phenomena within the Redfield approach we follow the real time dynamics of RET from the excited D towards A (Fig1 left panel) Moreover a newly derived multistate Redfield-Smoluchowski equation is used to investigate how the dynamical disorder induced by polar solvation affects RET (Fig1 right panel)
REFERENCES
1 F Terenziani A Painelli PhysChemChemPhys 17 13074-81 (2015) 2 C Sissa et al Phys Chem Chem Phys 2011 13 12734ndash12744 3 S Sanyal et al PhysChemChemPhys 2017 19 24979
Fig 1 Resonance
Energy Transfer in real
time Left Non-
adiabatic QUOTE
dynamics
following impulsive
excitation of the energy
donor the adiabatic
potential energy
surfaces are shown for
reference Right
temporal evolution of
the population of the
excited energy acceptor
in a frozen and liquid
polar solvent
I5
Towards an accurate computational photochemistry and photobiology the paradigmatic case of vision
Marco Garavelli1
1 Dipartimento di Chimica Industriale ldquoToso Montanarirdquo Viale del Risorgimento 4 40136 Bologna Italy 2 Affiliazione 2
marcogaravelliuniboit
ABSTRACT
The use of the computer to simulate light induced events in photoactive molecular materials has given access to a detailed description of the molecular motions and mechanisms underlying the reactivity of organic and bio-organic chromophores Thus different computational strategies and tools can now be operated like a ―virtual spectrometer to characterize and understand the photoinduced molecular deformation and reactivity of a given dye allowing for an accurate description of photochemicalphotobiological processes and a rational of the corresponding photophysical properties including time-resolved spectroscopy
This contribution reviews recent advances in this field by presenting methodological developments and applications in modeling the photophysicalphotochemical properties of organic chromophores and complex photoactive molecular architectures Retinal systems and visual proteins will be presented as a paradigmatic case [12] Hybrid QMMM calculations will be shown to be an elective tool for modeling photoinduced events and dynamics including tuningcontrolling effects of the environment For this purpose our new implementation of a general hybrid QMMM approach that is able to integrate some specialized softwares and acts as a flexible computational environment eventually allowing for so far inaccessible calculations (eg non-adiabatic molecular dynamics of unprecedented accuracy on large molecular materials) will be illustrated The information collected by these studies can be exploited for the design of novel photoactive molecular and soft materials including a novel paradigm of electrochromism for applications in a new generation of color tunable displays and e-ink devices Finally our latest achievements in developing (and modeling) non-linear bi-dimensional electronic spectroscopy as a novel diagnostic tool for tracking structuraldynamical problems in complex environments (eg biologically relevant systems such as proteins and DNA) will be presented [34]
REFERENCES
1 D Polli et al Nature 467 (2010) 440 2 B Demoulin et al JPCL 8 (2017) 4407 3 I Rivalta et al PCCP 16 (2014) 16865 4 I Rivalta et al JPCB 118 (2014) 8396
I6
Modellizzazione in fase condensata ad alte pressioni
Gianni Cardini
Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave di Firenze email giannicardiniunifiit
ABSTRACT
La modellizzazione delle proprietagrave strutturali e dinamiche di sistemi in fase condensata dipende essenzialmente dalla corretta descrizione del potenziale di interazione intermolecolare In simulazioni di dinamica molecolare1 si ricorre di solito a modelli di potenziale semi empirici o a metodi ab initio12 nella maggior parte dei casi basati sulla teoria del funzionale della densitagrave (DFT) Nel caso di sistemi sottoposti ad alte pressioni diventa cruciale una corretta descrizione delle interazioni a corto raggio e modelli che consentano eventualmente la rottura e formazione di legami chimici Verranno presentati alcuni risultati di simulazioni di dinamica molecolare ab initio con il metodo Car Parrinello Le simulazioni ab initio su fasi condensate basate su sistemi periodici sono dispendiose e pertanto condotte per tempi brevi e su campioni molto piccoli Inoltre nel campo delle alte pressioni gli sperimentali sono soliti interpretare i dati spettroscopici in termini di proprietagrave di singola molecola e necessitano di una modellizzazione possibilmente veloce per interpretare le loro misure Questo puograve essere ottenuto ricorrendo al metodo XP-PCM proposto da Cammi et al3 che consente di ottenere risultati qualitativi effettuando calcoli in condizioni estreme di pressione su singola molecola
REFERENCES
7 MP Allen amp DJ Tildesley Computer Simulation of Liquids Oxford University Press Oxford UK 2017 8 DMarx and J Hutter Ab Initio Molecular Dynamics Cambridge University Press Cambridge UK 2009 9 R Cammi et al Chem Phys 344 (2008) 135 R Cammi et al J ChemPhys 137 (2012) 154112
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
PROGRAMMA
Mercoledigrave 19 Settembre 1445-1500 Apertura del congresso
Sessione 1 Chairman Maria Cristina Menziani
1500-1545 Invited ndash Piero Decleva
Solving the Schroumldinger equation in a box wavepackets and continuum states
1545-1600 Sofia Canola ldquoVibrational and optical fingerprints of conjugated
biradicals from DFT and TDDFT calculationsrdquo
1600-1615 Marco Mendolicchio ldquoNew computational strategies for the calculation of
anharmonic force fieldsrdquo
1615-1630 Loredana Edith Daga ldquoOn Optimizing Gaussian Basis sets for Crystalline Solidsrdquo
1630-1700 Coffee Break (Atrio edificio H3)
Sessione 2 Chairman Benedetta Mennucci
1700-1745 Invited ndashFabrizio Santoro
Mixed quantumclassical description of the effects of nuclear motion in electronic
spectroscopy and ultrafast photophysics
1745-1800 Emanuele Coccia ldquoWave function-based approach to probe coherence in ultrafast
molecular processesrdquo
1800-1815 Amalia Velardo ldquoBand Shapes of Singlet-Triplet Transitionsrdquo
1815-1830 Laura Zanetti Polzi ldquoModeling amide I infrared spectra of proteins insights from
a perturbative approachrdquo
Giovedigrave 20 Settembre Sessione 3 Chairman Carlo Adamo
915-1000 Invited ndash Ana B Muntildeoz Garciacutea
Defective but effective the role of defects on the electrocatalytic performance of
oxide-based materials for energy conversion
1000-1015 Mario Prejanograve ldquoThe effect of distortions of a covalent enzymatic intermediate in
Human Transketolase a computational point of viewrdquo
1015-1030 Francesco Sessa ldquoLa3+
ion in EAN aqueous mixtures a MD-XAS investigation on
the effect of water concentrationrdquo
1030-1045 Diego Cesario ldquoSource of Cooperativity in Hydrogen-Bonded Supramolecular
Polymersrdquo
1045-1130 Coffee Break (Terrazza aula 1B primo piano edificio H3)
Sessione 4 Chairman Nino Polimeno
1130-1215 Invited ndashAnna Painelli
Solvent dynamics and energy transfer a real time description
1215-1230 Gloria Mazzone ldquoAiming at Color Prediction of Flexible Dyes in Aqueous
Solution Combined Molecular Dynamic and Quantum Mechanic approachesrdquo
1230-1245 Michele Guerrini ldquoSolid-state effects on the optical excitation of push-pull
molecular J-aggregates by first principles simulationsrdquo
1245-1300 Mirco Zerbetto ldquoPrevisione dei Tempi di Rilassamento NMR di Molecole
Flessibili Oligosaccaridi come Caso di Studiordquo
1300-1530 Pranzo + Poster session (Atrio edificio H3)
Sessione 5 Chairman Cristina Puzzarini
1530-1545 Francesco Faglioni ldquoSelf interaction charge delocalization electrolyte
ionizationrdquo
1545-1600 Mattia Anzola ldquoOptical spectra of molecular aggregates testing approximation
schemesrdquo
1600-1615 Martina De Vetta ldquoSimulations of a liposomal assisted delivery of the Temoporfin
photosensitizerrdquo
1615-1630 Matteo Masetti ldquoThe best of both worlds combining Markov State Models and
Path Collective Variables to describe protein-ligand bindingrdquo
1630-1645 Ida Ritacco ldquoThe mechanism of post-translation regulation of estrogen
biosynthesis in Breast cancer cells as revealed by atomic level multiscale
simulationsrdquo
1645-1700 Tommaso Giovannini ldquoDevelopment of Theoretical Approaches to Model the
Spectral Properties of Complex Systemsrdquo
1700-1745 Invited ndash Marco Garavelli
Towards an accurate computational photochemistry and photobiology the
paradigmatic case of vision
1745-1900 Assemblea della Divisione di Chimica Teorica e Computazionale della SCI
Venerdigrave 21 Settembre Sessione 6 Chairman Emilia Sicilia
915-1000 Invited ndash Gianni Cardini
Modellizzazione in fase condensata ad alte pressioni
1000-1015 Fortuna Ponte ldquoComputational investigation of the platinum(IV) anticancer
prodrugs reduction mechanism by L-ascorbic acidrdquo
1015-1030 Laura Falivene ldquoTuning Proximal and Remote Steric Effects in the
Rationalization of Catalytic Behaviorrdquo
1030-1045 Eduardo Schiavo ldquoInvestigating photoelectrochemical properties of dye-electrode
interfaces with density functional embedding theoryrdquo
1045-1100 Tainah Dorina Marforio ldquoCarbon nanotubes (CNTS) as nano-reactors
regioselectivity and kinetics control for the bromination of N-phenylacetamide A
QMMM investigationrdquo
1100-1145 Coffee Break (Atrio edificio H3)
Sessione 7 Sessione premi e medaglie Nordio ndash del Re ndash Scrocco ndash Roetti
Chairman Vincenzo Barone
1145-1200 Premio del Re Francesco Avanzini ldquoThe Quantum Molecular Trajectoryrdquo
1200-1230 Premio Scrocco Francesco Muniz-Miranda
Studies on the optoelectronic properties of metal nanoclusters and complexes
1230-1300 Premio Roetti Lorenzo Maschio
Quantum chemistry of crystalline solids using a local basis set the CRYSTAL
and CRYSCOR codes
1300 Conclusioni
Conferenze su invito Nome DipartimentoIstituzione Titolo contributo n
Piero Decleva DSCF Universitagrave di Trieste
Solving the Schroumldinger equation in a box wavepackets
and continuum states
I1
Fabrizio Santoro
ICCOM-CNR Area della Ricerca
del CNR di Pisa
Mixed quantumclassical description of the effects of
nuclear motion in electronic spectroscopy and ultrafast
photophysics
I2
Ana B Muntildeoz
Garciacutea
Dipartimento di Fisica ldquoEttore
Pancinirdquo Universitagrave di Napoli
Federico II
Defective but effective the role of defects on the
electrocatalytic performance of oxide-based materials for
energy conversion
I3
Anna Painelli
Dipartimento SCVSA Universitagrave
di Parma
Solvent dynamics and energy transfer
a real time description
I4
Marco Garavelli
Dipartimento di Chimica
Industriale ldquoToso Montanarirdquo
Bologna
Towards an accurate computational photochemistry and
photobiology the paradigmatic case of vision
I5
Gianni Cardini
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave di Firenze
Modellizzazione in fase condensata ad alte pressioni I6
Premi
Nome DipartimentoIstituzione Titolo contributo premio
Lorenzo Maschio Dipartimento di Chimica
Universitagrave di Torino
Quantum chemistry of crystalline solids using a local
basis set the CRYSTAL and CRYSCOR codes
Roetti
Francesco Muniz-
Miranda
Gent Universiteit Belgieuml Studies on the optoelectronic properties of metal
nanoclusters and complexes
Scrocco
Francesco Avanzini Dipartimento di Scienze
Chimiche Universitagrave degli Studi
di Padova
The Quantum Molecular Trajectory del Re
Contributi Orali
Nome DipartimentoIstituzione Titolo contributo n
Sofia Canola
Dipartimento di Chimica ldquoG
Ciamicianrdquo University of
Bologna via F Selmi 2 Bologna
Italy
Vibrational and optical fingerprints of conjugated
biradicals from DFT and TDDFT calculations
O1
Marco
Mendolicchio
Scuola Normale Superiore I-
56126 Pisa Italy
New computational strategies for the calculation of
anharmonic force fields
O2
Loredana Edith
Daga
Diparimento di Chimica
Universitagrave di Torino
On Optimizing Gaussian Basis sets for Crystalline Solids O3
Emanuele Coccia
Dipartimento di Scienze
Chimiche Universitagrave di Padova
via Marzolo 1 Padova Italy
Wave function-based approach to probe coherence in
ultrafast molecular processes
O4
Amalia Velardo
Dipartimento Chimica e Biologia
ldquoAdolfo Zambellirdquo Universitagrave
degli Studi di Salerno Via G
Paolo II 84084-Fisciano Italy
Band Shapes of Singlet-Triplet Transitions
O5
Laura Zanetti-Polzi
Department of Physical and
Chemical Sciences University of
LAquila Via Vetoio (Coppito1)
67010 LAquila Italy
Modeling amide I infrared spectra of proteins insights
from a perturbative approach
O6
Mario Prejanograve
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende (CS) Italia
The effect of distortions of a covalent enzymatic
intermediate in Human Transketolase a computational
point of view
O7
F Sessa
Department of Chemistry
University of Rome ldquoLa
Sapienzardquo Rome Italy
La3+ ion in EAN aqueous mixtures a MD-XAS
investigation on the effect of water concentration
O8
Diego Cesario
- Department of Chemistry and
Pharmaceutical Sciences and
Amsterdam Center for Multiscale
Modeling Vrije Universiteit
Amsterdam De Boelelaan 1083
1081 HV Amsterdam The
Netherlands
- Department of Chemistry
Biology and Biotechnology
University of Perugia
via Elce di Sotto 8 I-06123
Perugia Italy
Source of Cooperativity in Hydrogen-Bonded
Supramolecular Polymers
O9
Gloria Mazzone Chimie ParisTech PSL Research
University CNRS Institut de
Recherche de Chimie Paris Paris
France
Aiming at Color Prediction of Flexible Dyes in Aqueous
Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
O10
Michele Guerrini
Dipartimento FIM Universitagrave di
Modena e Reggio Emilia Italy
Solid-state effects on the optical excitation of push-pull
molecular J-aggregates by first principles simulations
O11
Mirco Zerbetto
Dipartimento di Scienze
Chimiche Universitagrave degli Studi
di Padova Padova 35313 Italia
Previsione dei Tempi di Rilassamento NMR di Molecole
Flessibili Oligosaccaridi come Caso di Studio
O12
F Faglioni
DSCG Univ of Modena and
Reggio Emilia Modena Italy
Self interaction charge delocalization electrolyte
ionization
O13
Mattia Anzola
Dipartimento di Scienze
Chimiche della Vita e della
Sostenibilitagrave Ambientale
Universitagrave degli Studi di Parma
Italy
Optical spectra of molecular aggregates testing
approximation schemes
O14
Martina De Vetta
-Institute of Theoretical
Chemistry Faculty of Chemistry
University of Vienna Waumlhringer
Str 17 A-1090 Vienna Austria
-Departamento de u mica
Universidad Aut noma de Madrid
Francisco Tomaacutes y Valiente 7
28049 Cantoblanco Madrid Spain
Simulations of a liposomal assisted delivery of the
Temoporfin photosensitizer
O15
Matteo Masetti Department of Pharmacy and
Biotechnology (FaBiT) Alma
Mater Studiorum ndash University of
Bologna Italy
The best of both worlds combining Markov State Models
and Path Collective Variables to describe protein-ligand
binding
O16
Ida Ritacco
CNR-IOM co SISSA via
Bonomea 265 34136 Trieste Italy
The mechanism of post-translation regulation of estrogen
biosynthesis in Breast cancer cells as revealed by atomic
level multiscale simulations
O17
Tommaso
Giovannini
Scuola Normale Superiore Piazza
dei Cavalieri 7 Pisa IT
Development of Theoretical Approaches to Model the
Spectral Properties of Complex Systems
O18
Fortuna Ponte
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria
Computational investigation of the platinum(IV)
anticancer prodrugs reduction mechanism by L-ascorbic
acid
O19
Laura Falivene
KAUST Catalysis Center King
Abdullah University of Science
and Technology Thuwal 23955-
6900 Saudi Arabia
Tuning Proximal and Remote Steric Effects in the
Rationalization of Catalytic Behavior
O20
E Schiavo
Department of Chemical Sciences
University of Naples Federico II
Comp Univ Monte SantrsquoAngelo
Via Cintia 21 80126 Naples Italy
Investigating photoelectrochemical properties of dye-
electrode interfaces with density functional embedding
theory
O21
Tainah Dorina
Marforio
Dipartimento di Chimica ldquoG
Ciamicianrdquo Alma Mater
Studiorum ndash Universitagrave di
Bologna via Selmi 2 40126
Bologna
Italy
CARBON NANOTUBES (CNTS) AS NANO-
REACTORS
REGIOSELECTIVITY AND KINETICS CONTROL
FOR
THE BROMINATION OF N-PHENYLACETAMIDE
A QMMM INVESTIGATION
O22
Poster Nome DipartimentoIstituzione Titolo contributo n
F Cappelluti
Universitagrave degli Studi dellrsquoAquila
- LrsquoAquila
F-RESP a fast and accurate polarizable force field P1
Francesco Tavanti
Department of Chemical and
Geological Sciences University of
Modena and Reggio Emilia Via
Campi 103 41125
Modena Italy
Natural compounds for Alzheimerrsquos disease treatment a
classical
Molecular Dynamics investigation
P2
E Bernes
Department of Chemical and
Pharmaceutical Sciences
University of Trieste 34127
Trieste Italy
Core-Electron Excitations in Dibenzothiophene
Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
P3
Baiano C
Department of Chemical Sciences
University of Naples Federico II
Ab initio characterization of CO2 photoreduction
mechanism at CuFeO2 delafossite electrode
P4
Davide Accomasso
Department of Chemistry and
Industrial Chemistry University
of Pisa Italy
Seeking new materials for singlet fission
covalent dimers as an alternative to molecular crystals
P5
Henry Adenusi
Chemistry Department University
of Rome ldquoLa Sapienzardquo Italy
Proton transfer mechanisms in protic ionic liquids P6
Giorgia Beata
Dipartimento di Chimica
Universitagrave di Torino Via Giuria 7
I-10125 Torino Italy
CRYSPLOT a new tool to visualize physical and
chemical properties of crystalline solids
P7
Marco Pagliai
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave degli Studi di
Firenze via della Lastruccia 3
50019 Sesto Fiorentino (FI) Italy
Molecular dynamics simulations of zinc proteins a
new force field
P8
Eslam M Moustafa
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria I-87036 Aracavacta
di Rende (CS) Italy
Reduction of Pt(IV) anticancer drugs a DFT mechanistic
study
P9
Alessandro Landi
Dipartimento di Chimica e
Biologia Adolfo Zambelli
Universitagrave di Salerno Via
Giovanni Paolo II I-84084
Fisciano (SA) Italy
Rapid evaluation of dynamic disorder in organic
semiconductors
P10
Isabella Romeo
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende I-87036
Italy
De novo proteins Insights from the theoretical
investigations
P11
Marina
Macchiagodena
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave degli Studi di
Firenze Via della Lastruccia 3 I-
50019 Sesto Fiorentino Italy
Improved force fields for molecular dynamics
simulations of zinc proteins
P12
Marco Fusegrave
Scuola Normale Superiore Piazza
dei Cavalieri 7 56126 Pisa Italy
Computational simulation of vibrationally resolved
spectra for spin‐forbidden transitionsforbidden transitions
P13
Tiziana Marino
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende I-87036
Italy
De novo proteins Insights from the theoretical
investigations
P14
Matteo Capone
Universitagrave dellrsquoAquila Italia Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
P15
J FREGONI
Dipartimento di scienze Fisiche
Informatiche e Matematiche
University of Modena and Reggio
Emilia I-41125 Modena Italy
Manipulating azobenzene photoisomerization
through strong light-molecule coupling
P16
Irene Conti
Dipartimento di Chimica
Industriale ldquo Toso Montanarirdquo
Universita di Bologna Viale del
Risorgimento 4 I-40136 Bologna
Italy
Excitonic State evolution of DNA Stacked Thymines
Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
P17
Andrea Le Donne
Chemistry department University
of Rome ldquoLa Sapienzardquo Rome
Italy
Ionic Liquids and Proton Transfer A Computational
Study to Understand Dynamic Processes
P18
Franco Egidi
Scuola Normale Superiore 56126
Pisa Italy
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
P19
Arianna Massaro
Department of Chemical Science
University of Naples ldquoFederico
IIrdquo via Cintia 21 80126 Naples
Italy
Unveiling the role of structural features in Na insertion
mechanism at anatase surfaces new insights for Na-ion
batteries development
P20
Alessandro Landi
Dipartimento di Chimica e
Biologia Adolfo Zambelli
Universitagrave di Salerno Via
Giovanni Paolo II I-84084
Fisciano (SA) Italy
Hole Mobility in Organic Semiconductors A Second-
Order Cumulant Approach
P21
Mariagrazia Fortino
Universitagrave di Modena e Reggio
Emilia Modena 41125 Italy
On the Simulation of Vibrationally Resolved Electronic
Spectra of medium-size molecules the case of Styryl
Substituted BODIPYs
P22
Marco Medves Dipdi Scienze Chimiche e
Farmaceutiche Universitagrave di
Trieste
Theoretical Study on the Circular Dichroism of Chiral
Bimetallic Clusters Ag-Au
P23
Jonathan Campeggio
Universitagrave degli Studi di Padova DiTe2 Calcolo del tensore di diffusione per molecole
flessibili
P24
Edoardo Jun
Mattioli
Chemistry Department ldquoG
Ciamicianrdquo University of Bologna
Computational Investigation of Competitive
Reaction Mechanisms inside Carbon Nanotubes
P25
Sergio Rampino
SMART Laboratory Scuola
Normale Superiore Piazza dei
Cavalieri 7 56126 Pisa
Combined Orbital-spaceReal-space Analysis of
Chemical Bonding through Virtual Reality
P26
Josephine Alba Dipdi Chimica Universitagrave di
Roma La Sapienza
Efficient and Accurate Modelling of Conformational
Transitions in proteins comparison between two Src
kinase proteins
P27
Abstracts delle conferenze su invito
I1
Solving the Schroumldinger equation in a box wavepackets and continuum states
Piero Decleva
DSCF Universitarsquo di Trieste declevaunitsit
ABSTRACT
Nelle molecole gli stati elettronici piursquo bassi decadono esponenzialmente con unrsquoestensione spaziale molto limitata Questo non ersquo piursquo vero per
- Stati Rydberg con alti numeri quantici - Stati del continuo - Pacchetti generati da impulsi elettromagnetici molto intensi
In tal caso le basi LCAO costruite da GTO o STO risultano inadeguate e sono necessari approcci alternativi sia funzioni di base diverse sia uso di griglie numeriche Per lo studio del continuo elettronico abbiamo da tempo sviluppato un set basato sullrsquouso di B-spline [1] come funzioni radiali adoperate nel modo LCAO convenzionale che si ersquo dimostrato assai flessibile e accurato Queste forniscono unrsquoeccellente rappresentazione delle soluzioni dellrsquoequazione di Schroumldinger allrsquointerno di una sfera di raggio prefissato arbitrario Calcoli dei parametri di fotoionizzazione molecolare a livello DFT [2] o TDDFT [3] forniscono generalmente risultati in buon accordo con lrsquoesperimento anche per sistemi relativamente grandi e per un gran numero di osservabili di fotoionizzazione sezioni drsquourto distribuzioni angolari di molecole con orientazione fissa o casuale parametri non-dipolari effetti di interferenza e diffrazione parametri chirali Ersquo stata anche applicata a fotoionizzazione risolta nel tempo da stati eccitati in esperimenti pump-probe e alla generazione di pacchetti di cationi da impulsi ultraveloci Piursquo recentemente la base ersquo stata applicata al calcolo di pacchetti drsquoonda eccitati da impulsi laser in regime non perturbativo Durante lrsquoimpulso lrsquoescursione dellrsquoelettrone puorsquo raggiungere migliaia di unitarsquo atomiche ma lrsquoapproccio ersquo numericamente molto stabile e si presta bene all propagazione del pacchetto per risoluzione dellrsquoequazione temporale Ersquo stata considerata la ionizzazione totale in funzione dellrsquoorientazione del campo rispetto alla molecola [4] il calcolo dello spettro di elettroni risolto in energia ed angolo attraverso la proiezione sugli autostati del continuo la rivelazione di pacchetti elettronici coerenti in esperimenti pump-probe agli attosecondi [5] la generazione di armoniche alte (HHG) [6] Verranno illustrati alcuni risultati recenti e discusse le linee di sviluppo
REFERENCES
1 H Bachau E Cormier P Decleva J E Hansen and F Martin ldquoApplications of B-splines in Atomic and Molecular Physicsrdquo
Reports on Progress in Physics 64 1815 (2001)
2 D Toffoli M Stener G Fronzoni and P Decleva ldquoConvergenge of the Multicenter B-spline DFT approach for the continuumrdquo
Chem Phys 276 25 (2002)
3 M Stener G Fronzoni and P Decleva ldquoTime-dependent density-functional theory for molecular photoionization with
noniterative algorithm and multicenter B-spline basis set CS2 and C6H6 case studiesrdquoJ Chem Phys 122 (2005) 234301
4 S Petretti YV Vanne A Saenz A Castro and P Decleva ldquoAlignment-Dependent Ionization of N2 O2 and CO2 in Intense
Laser Fieldsrdquo Phys Rev Letters 104 (2010) 223001
5 M Ruberti P Decleva and V Averbukh ldquoMulti-channel dynamics and correlation-driven inter-channel couplings in high
harmonic generation spectra of aligned CO2 molecule ab initio Time Dependent B-spline ADC ab initio analysisrdquo Phys Chem
Chem Phys 20 (2018) 8311
6 E Plesiat M Lara-Astiaso P Decleva A Palacios and F Martin ldquoReal-time determination of ultrafast charge dynamics in
tetrafluoromethane from attosecond pump-probe photoelectron spectroscopyrdquo Chem Eur J 242018 xxx
I2
Mixed quantumclassical description of the effects of nuclear motion in electronic spectroscopy and ultrafast
photophysics
Fabrizio Santoro1
1 ICCOM-CNR Area della Ricerca del CNR di Pisa Italy 2 Affiliazione 2
fabriziosantoroiccomcnrit
ABSTRACT
Quantum nuclear effects can play a relevant role in determining the shape of electronic spectra and the fate of the photoexcited dynamics in molecular systems Recent advancements in fully quantum vibronic approaches for the computation of spectra [12] and in quantum-dynamical (QD) approaches like those provided by the MCTDH method [3-5] allow an efficient description of such effects even in large systems if they are rigid (harmonic) and in gas phase Flexible systems or systems embedded in solvents or in heterogenoeus media possibly establishing with them specific interactions represent a challenge for fully quantum treatments of nuclear motions Classical and semi-classical trajectory based approaches are very well suited to deal with these cases but they neglect quantum nuclear effects We believe that the development of wise mixed quantum classical (MQC) approaches may represent a suitable framework to overcome some of these present limitations In this contribution we present our recent work in this field In electronic spectroscopy we introduced mixed schemes that separate fast and slow degrees of freedom (DoF) on the grounds of an adiabatic approximation and treat the fast DoF at quantum level and the slow ones (including the solvent) at classical level The spectra are then naturally expressed as an average of vibronic spectra involving along the fast DoF over the distribution of the classical DoF [5-7] Extending these ideas to ultrafast photophysical processes we recently proposed a MQC approach to introduce environmental dynamical effects in QD simulations In its simplest version all the solute degrees of freedom are represented by a wavepacket moving according to nonadiabatic quantum dynamics while the motion of an explicit solvent model is described by an ensemble of classical trajectories The core idea of the method is to describe the mutual coupling of the solute and solvent dynamics within a mean-field framework In this way the Hamiltonians of both the quantum and classical subsystems contain time-dependent terms due to the interaction with the other subset and the quantum and classical equations of motions are solved simultaneously We will discuss the potentialities limitations and possible perspectives of these methods with a number of test applications
REFERENCES
1 Barone V WIREs Comput Mol Sci 2016 6 86-110 2 Santoro F Jacquemin D WIREs Comput Mol Sci 2016 6 460-486 3 Wang H Thoss M J Chem Phys 2003 119 1289minus1299 Vendrell O Meyer H-D J Chem Phys 2011 134 044135 4 Beck M H J ckle A Worth G A Meyer H-D Phys Rep 2000 324 1minus105 5 CerezoJ Avila F Prampolini G Santoro F J Chem Theory Comput 2015 11 5810ndash5825
6 Cerezo J Mazzeo G Longhi G Abbate S Santoro F J Phys Chem Lett 2016 7 4891‐4897 7 Cerezo J Aranda D Avila F Mazzeo G Longhi G Abbate S Santoro F Chirality 2018 30 730ndash743 8 Cerezo J Liu Y Lin N Zhao X Improta R Santoro F J Chem Theory Comput 201814 820ndash832
I3
Defective but effective the role of defects on the electrocatalytic performance of oxide-based materials
for energy conversion
Ana B Muntildeoz Garciacutea1
1 Dipartimento di Fisica ldquoEttore Pancinirdquo Universitagrave di Napoli Federico II
Comp Univ Monte S Angelo via Cintia 21 80126 Napoli (Italia)
anabelenmunozgarciauninait
ABSTRACT
Ab initio simulations play an increasingly important role in materials sciences In the energy conversion scenario computational modeling can elucidate with atomic resolution the subtle composition-structure-property relationships behind the performance of functional materials and complex interfaces In heterogeneous electrocatalysis the underlying bulk and surface chargemass transport events are often strongly dependent on the presenceabsence of structural defects Thus a deep knowledge of defect chemistry is key for understanding tuning and optimizing the properties of different catalysts In particular this contribution will report recent advances in the DFT-based characterization of the role of defects in strongly correlated oxides as electrodes in electrocatalytic devices Three case studies will be presented (i) a new triple-conducting oxide based on Sr2Fe15Mo05O6 perovskite with promising bifunctional catalytic activity towards oxygen reduction and evolution reactions [1-3] (ii) Fe-doped ZrO2 for low temperature PEMFCs [4] and (iii) CuFeO2 delafossite for CO2 photoreduction [5] In all these cases we will discuss how surface oxygen vacancies -boosted by aliovalent doping- can improve the electrode performance and change product selectivity In conclusion this contribution will highlight the merits of computationally driven materials discovery in the context of energy conversion devices pointing out the importance of the necessary interplay between theory and experiment
REFERENCES
1 ABMG D Bugaris M Pavone J P Hodges A Huq F Chen H-C zur Loye E A Carter J Am Chem Soc 134 6826 (2012) 2 ABMG M Pavone Chem Mater 28 490 (2016) 3 ABMG M Pavone J Mater Chem A 5 12735 (2017) 4 P Madkikar D Menga G Harzer T Mittermeier A Siebel F E Wagner M Merz S Schuppler P Nagel ABMG M Pavone H A Gasteiger M Piana Submitted 5 J Gu A Wuttig J W Krizan Y Hu Z M Detweller R J Cava A B Bocarsly J Phys Chem C 117 12415 (2013)
I4
Solvent dynamics and energy transfer a real time description
Anna Painelli Francesco Di Maiolo
Dipartimento SCVSA Universitagrave di Parma annapainelliuniprit
ABSTRACT
Energy dissipation and relaxation phenomena are crucial to describe the dynamics of excited states The interaction of a molecule with the environment (the bath) is pivotal in this respect bringing theoretical chemistry towards the field of open quantum systems Several strategies are available to quantitatively describe the system-bath interaction most often based on the dynamics of the reduced density matrix Vibrational degrees of freedom must be explicitly described to address internal conversion and the huge dimension of the resulting basis imposes dramatic approximations to the calculation Here we face the problem adopting an essential state model (ESM) description of the molecular systems ESMs proved successful in describing low-energy linear and non-linear optical spectra of several families of organic dyes in terms of a minimal number of electronic states coupled to few effective vibrational modes ESMs successfully account for polar solvation and for intermolecular interactions in molecular aggregates and in energy transfer systems (1 2 3)
Here we present a dynamical non-adiabatic model for Resonance Energy Transfer (RET) Specifically we consider two dyes an energy donor (D) and an energy acceptor (A) Each dye corresponds to a push-pull chromophore described in terms of two electronic states coupled to a single effective vibration Accounting for dissipation phenomena within the Redfield approach we follow the real time dynamics of RET from the excited D towards A (Fig1 left panel) Moreover a newly derived multistate Redfield-Smoluchowski equation is used to investigate how the dynamical disorder induced by polar solvation affects RET (Fig1 right panel)
REFERENCES
1 F Terenziani A Painelli PhysChemChemPhys 17 13074-81 (2015) 2 C Sissa et al Phys Chem Chem Phys 2011 13 12734ndash12744 3 S Sanyal et al PhysChemChemPhys 2017 19 24979
Fig 1 Resonance
Energy Transfer in real
time Left Non-
adiabatic QUOTE
dynamics
following impulsive
excitation of the energy
donor the adiabatic
potential energy
surfaces are shown for
reference Right
temporal evolution of
the population of the
excited energy acceptor
in a frozen and liquid
polar solvent
I5
Towards an accurate computational photochemistry and photobiology the paradigmatic case of vision
Marco Garavelli1
1 Dipartimento di Chimica Industriale ldquoToso Montanarirdquo Viale del Risorgimento 4 40136 Bologna Italy 2 Affiliazione 2
marcogaravelliuniboit
ABSTRACT
The use of the computer to simulate light induced events in photoactive molecular materials has given access to a detailed description of the molecular motions and mechanisms underlying the reactivity of organic and bio-organic chromophores Thus different computational strategies and tools can now be operated like a ―virtual spectrometer to characterize and understand the photoinduced molecular deformation and reactivity of a given dye allowing for an accurate description of photochemicalphotobiological processes and a rational of the corresponding photophysical properties including time-resolved spectroscopy
This contribution reviews recent advances in this field by presenting methodological developments and applications in modeling the photophysicalphotochemical properties of organic chromophores and complex photoactive molecular architectures Retinal systems and visual proteins will be presented as a paradigmatic case [12] Hybrid QMMM calculations will be shown to be an elective tool for modeling photoinduced events and dynamics including tuningcontrolling effects of the environment For this purpose our new implementation of a general hybrid QMMM approach that is able to integrate some specialized softwares and acts as a flexible computational environment eventually allowing for so far inaccessible calculations (eg non-adiabatic molecular dynamics of unprecedented accuracy on large molecular materials) will be illustrated The information collected by these studies can be exploited for the design of novel photoactive molecular and soft materials including a novel paradigm of electrochromism for applications in a new generation of color tunable displays and e-ink devices Finally our latest achievements in developing (and modeling) non-linear bi-dimensional electronic spectroscopy as a novel diagnostic tool for tracking structuraldynamical problems in complex environments (eg biologically relevant systems such as proteins and DNA) will be presented [34]
REFERENCES
1 D Polli et al Nature 467 (2010) 440 2 B Demoulin et al JPCL 8 (2017) 4407 3 I Rivalta et al PCCP 16 (2014) 16865 4 I Rivalta et al JPCB 118 (2014) 8396
I6
Modellizzazione in fase condensata ad alte pressioni
Gianni Cardini
Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave di Firenze email giannicardiniunifiit
ABSTRACT
La modellizzazione delle proprietagrave strutturali e dinamiche di sistemi in fase condensata dipende essenzialmente dalla corretta descrizione del potenziale di interazione intermolecolare In simulazioni di dinamica molecolare1 si ricorre di solito a modelli di potenziale semi empirici o a metodi ab initio12 nella maggior parte dei casi basati sulla teoria del funzionale della densitagrave (DFT) Nel caso di sistemi sottoposti ad alte pressioni diventa cruciale una corretta descrizione delle interazioni a corto raggio e modelli che consentano eventualmente la rottura e formazione di legami chimici Verranno presentati alcuni risultati di simulazioni di dinamica molecolare ab initio con il metodo Car Parrinello Le simulazioni ab initio su fasi condensate basate su sistemi periodici sono dispendiose e pertanto condotte per tempi brevi e su campioni molto piccoli Inoltre nel campo delle alte pressioni gli sperimentali sono soliti interpretare i dati spettroscopici in termini di proprietagrave di singola molecola e necessitano di una modellizzazione possibilmente veloce per interpretare le loro misure Questo puograve essere ottenuto ricorrendo al metodo XP-PCM proposto da Cammi et al3 che consente di ottenere risultati qualitativi effettuando calcoli in condizioni estreme di pressione su singola molecola
REFERENCES
7 MP Allen amp DJ Tildesley Computer Simulation of Liquids Oxford University Press Oxford UK 2017 8 DMarx and J Hutter Ab Initio Molecular Dynamics Cambridge University Press Cambridge UK 2009 9 R Cammi et al Chem Phys 344 (2008) 135 R Cammi et al J ChemPhys 137 (2012) 154112
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
Giovedigrave 20 Settembre Sessione 3 Chairman Carlo Adamo
915-1000 Invited ndash Ana B Muntildeoz Garciacutea
Defective but effective the role of defects on the electrocatalytic performance of
oxide-based materials for energy conversion
1000-1015 Mario Prejanograve ldquoThe effect of distortions of a covalent enzymatic intermediate in
Human Transketolase a computational point of viewrdquo
1015-1030 Francesco Sessa ldquoLa3+
ion in EAN aqueous mixtures a MD-XAS investigation on
the effect of water concentrationrdquo
1030-1045 Diego Cesario ldquoSource of Cooperativity in Hydrogen-Bonded Supramolecular
Polymersrdquo
1045-1130 Coffee Break (Terrazza aula 1B primo piano edificio H3)
Sessione 4 Chairman Nino Polimeno
1130-1215 Invited ndashAnna Painelli
Solvent dynamics and energy transfer a real time description
1215-1230 Gloria Mazzone ldquoAiming at Color Prediction of Flexible Dyes in Aqueous
Solution Combined Molecular Dynamic and Quantum Mechanic approachesrdquo
1230-1245 Michele Guerrini ldquoSolid-state effects on the optical excitation of push-pull
molecular J-aggregates by first principles simulationsrdquo
1245-1300 Mirco Zerbetto ldquoPrevisione dei Tempi di Rilassamento NMR di Molecole
Flessibili Oligosaccaridi come Caso di Studiordquo
1300-1530 Pranzo + Poster session (Atrio edificio H3)
Sessione 5 Chairman Cristina Puzzarini
1530-1545 Francesco Faglioni ldquoSelf interaction charge delocalization electrolyte
ionizationrdquo
1545-1600 Mattia Anzola ldquoOptical spectra of molecular aggregates testing approximation
schemesrdquo
1600-1615 Martina De Vetta ldquoSimulations of a liposomal assisted delivery of the Temoporfin
photosensitizerrdquo
1615-1630 Matteo Masetti ldquoThe best of both worlds combining Markov State Models and
Path Collective Variables to describe protein-ligand bindingrdquo
1630-1645 Ida Ritacco ldquoThe mechanism of post-translation regulation of estrogen
biosynthesis in Breast cancer cells as revealed by atomic level multiscale
simulationsrdquo
1645-1700 Tommaso Giovannini ldquoDevelopment of Theoretical Approaches to Model the
Spectral Properties of Complex Systemsrdquo
1700-1745 Invited ndash Marco Garavelli
Towards an accurate computational photochemistry and photobiology the
paradigmatic case of vision
1745-1900 Assemblea della Divisione di Chimica Teorica e Computazionale della SCI
Venerdigrave 21 Settembre Sessione 6 Chairman Emilia Sicilia
915-1000 Invited ndash Gianni Cardini
Modellizzazione in fase condensata ad alte pressioni
1000-1015 Fortuna Ponte ldquoComputational investigation of the platinum(IV) anticancer
prodrugs reduction mechanism by L-ascorbic acidrdquo
1015-1030 Laura Falivene ldquoTuning Proximal and Remote Steric Effects in the
Rationalization of Catalytic Behaviorrdquo
1030-1045 Eduardo Schiavo ldquoInvestigating photoelectrochemical properties of dye-electrode
interfaces with density functional embedding theoryrdquo
1045-1100 Tainah Dorina Marforio ldquoCarbon nanotubes (CNTS) as nano-reactors
regioselectivity and kinetics control for the bromination of N-phenylacetamide A
QMMM investigationrdquo
1100-1145 Coffee Break (Atrio edificio H3)
Sessione 7 Sessione premi e medaglie Nordio ndash del Re ndash Scrocco ndash Roetti
Chairman Vincenzo Barone
1145-1200 Premio del Re Francesco Avanzini ldquoThe Quantum Molecular Trajectoryrdquo
1200-1230 Premio Scrocco Francesco Muniz-Miranda
Studies on the optoelectronic properties of metal nanoclusters and complexes
1230-1300 Premio Roetti Lorenzo Maschio
Quantum chemistry of crystalline solids using a local basis set the CRYSTAL
and CRYSCOR codes
1300 Conclusioni
Conferenze su invito Nome DipartimentoIstituzione Titolo contributo n
Piero Decleva DSCF Universitagrave di Trieste
Solving the Schroumldinger equation in a box wavepackets
and continuum states
I1
Fabrizio Santoro
ICCOM-CNR Area della Ricerca
del CNR di Pisa
Mixed quantumclassical description of the effects of
nuclear motion in electronic spectroscopy and ultrafast
photophysics
I2
Ana B Muntildeoz
Garciacutea
Dipartimento di Fisica ldquoEttore
Pancinirdquo Universitagrave di Napoli
Federico II
Defective but effective the role of defects on the
electrocatalytic performance of oxide-based materials for
energy conversion
I3
Anna Painelli
Dipartimento SCVSA Universitagrave
di Parma
Solvent dynamics and energy transfer
a real time description
I4
Marco Garavelli
Dipartimento di Chimica
Industriale ldquoToso Montanarirdquo
Bologna
Towards an accurate computational photochemistry and
photobiology the paradigmatic case of vision
I5
Gianni Cardini
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave di Firenze
Modellizzazione in fase condensata ad alte pressioni I6
Premi
Nome DipartimentoIstituzione Titolo contributo premio
Lorenzo Maschio Dipartimento di Chimica
Universitagrave di Torino
Quantum chemistry of crystalline solids using a local
basis set the CRYSTAL and CRYSCOR codes
Roetti
Francesco Muniz-
Miranda
Gent Universiteit Belgieuml Studies on the optoelectronic properties of metal
nanoclusters and complexes
Scrocco
Francesco Avanzini Dipartimento di Scienze
Chimiche Universitagrave degli Studi
di Padova
The Quantum Molecular Trajectory del Re
Contributi Orali
Nome DipartimentoIstituzione Titolo contributo n
Sofia Canola
Dipartimento di Chimica ldquoG
Ciamicianrdquo University of
Bologna via F Selmi 2 Bologna
Italy
Vibrational and optical fingerprints of conjugated
biradicals from DFT and TDDFT calculations
O1
Marco
Mendolicchio
Scuola Normale Superiore I-
56126 Pisa Italy
New computational strategies for the calculation of
anharmonic force fields
O2
Loredana Edith
Daga
Diparimento di Chimica
Universitagrave di Torino
On Optimizing Gaussian Basis sets for Crystalline Solids O3
Emanuele Coccia
Dipartimento di Scienze
Chimiche Universitagrave di Padova
via Marzolo 1 Padova Italy
Wave function-based approach to probe coherence in
ultrafast molecular processes
O4
Amalia Velardo
Dipartimento Chimica e Biologia
ldquoAdolfo Zambellirdquo Universitagrave
degli Studi di Salerno Via G
Paolo II 84084-Fisciano Italy
Band Shapes of Singlet-Triplet Transitions
O5
Laura Zanetti-Polzi
Department of Physical and
Chemical Sciences University of
LAquila Via Vetoio (Coppito1)
67010 LAquila Italy
Modeling amide I infrared spectra of proteins insights
from a perturbative approach
O6
Mario Prejanograve
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende (CS) Italia
The effect of distortions of a covalent enzymatic
intermediate in Human Transketolase a computational
point of view
O7
F Sessa
Department of Chemistry
University of Rome ldquoLa
Sapienzardquo Rome Italy
La3+ ion in EAN aqueous mixtures a MD-XAS
investigation on the effect of water concentration
O8
Diego Cesario
- Department of Chemistry and
Pharmaceutical Sciences and
Amsterdam Center for Multiscale
Modeling Vrije Universiteit
Amsterdam De Boelelaan 1083
1081 HV Amsterdam The
Netherlands
- Department of Chemistry
Biology and Biotechnology
University of Perugia
via Elce di Sotto 8 I-06123
Perugia Italy
Source of Cooperativity in Hydrogen-Bonded
Supramolecular Polymers
O9
Gloria Mazzone Chimie ParisTech PSL Research
University CNRS Institut de
Recherche de Chimie Paris Paris
France
Aiming at Color Prediction of Flexible Dyes in Aqueous
Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
O10
Michele Guerrini
Dipartimento FIM Universitagrave di
Modena e Reggio Emilia Italy
Solid-state effects on the optical excitation of push-pull
molecular J-aggregates by first principles simulations
O11
Mirco Zerbetto
Dipartimento di Scienze
Chimiche Universitagrave degli Studi
di Padova Padova 35313 Italia
Previsione dei Tempi di Rilassamento NMR di Molecole
Flessibili Oligosaccaridi come Caso di Studio
O12
F Faglioni
DSCG Univ of Modena and
Reggio Emilia Modena Italy
Self interaction charge delocalization electrolyte
ionization
O13
Mattia Anzola
Dipartimento di Scienze
Chimiche della Vita e della
Sostenibilitagrave Ambientale
Universitagrave degli Studi di Parma
Italy
Optical spectra of molecular aggregates testing
approximation schemes
O14
Martina De Vetta
-Institute of Theoretical
Chemistry Faculty of Chemistry
University of Vienna Waumlhringer
Str 17 A-1090 Vienna Austria
-Departamento de u mica
Universidad Aut noma de Madrid
Francisco Tomaacutes y Valiente 7
28049 Cantoblanco Madrid Spain
Simulations of a liposomal assisted delivery of the
Temoporfin photosensitizer
O15
Matteo Masetti Department of Pharmacy and
Biotechnology (FaBiT) Alma
Mater Studiorum ndash University of
Bologna Italy
The best of both worlds combining Markov State Models
and Path Collective Variables to describe protein-ligand
binding
O16
Ida Ritacco
CNR-IOM co SISSA via
Bonomea 265 34136 Trieste Italy
The mechanism of post-translation regulation of estrogen
biosynthesis in Breast cancer cells as revealed by atomic
level multiscale simulations
O17
Tommaso
Giovannini
Scuola Normale Superiore Piazza
dei Cavalieri 7 Pisa IT
Development of Theoretical Approaches to Model the
Spectral Properties of Complex Systems
O18
Fortuna Ponte
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria
Computational investigation of the platinum(IV)
anticancer prodrugs reduction mechanism by L-ascorbic
acid
O19
Laura Falivene
KAUST Catalysis Center King
Abdullah University of Science
and Technology Thuwal 23955-
6900 Saudi Arabia
Tuning Proximal and Remote Steric Effects in the
Rationalization of Catalytic Behavior
O20
E Schiavo
Department of Chemical Sciences
University of Naples Federico II
Comp Univ Monte SantrsquoAngelo
Via Cintia 21 80126 Naples Italy
Investigating photoelectrochemical properties of dye-
electrode interfaces with density functional embedding
theory
O21
Tainah Dorina
Marforio
Dipartimento di Chimica ldquoG
Ciamicianrdquo Alma Mater
Studiorum ndash Universitagrave di
Bologna via Selmi 2 40126
Bologna
Italy
CARBON NANOTUBES (CNTS) AS NANO-
REACTORS
REGIOSELECTIVITY AND KINETICS CONTROL
FOR
THE BROMINATION OF N-PHENYLACETAMIDE
A QMMM INVESTIGATION
O22
Poster Nome DipartimentoIstituzione Titolo contributo n
F Cappelluti
Universitagrave degli Studi dellrsquoAquila
- LrsquoAquila
F-RESP a fast and accurate polarizable force field P1
Francesco Tavanti
Department of Chemical and
Geological Sciences University of
Modena and Reggio Emilia Via
Campi 103 41125
Modena Italy
Natural compounds for Alzheimerrsquos disease treatment a
classical
Molecular Dynamics investigation
P2
E Bernes
Department of Chemical and
Pharmaceutical Sciences
University of Trieste 34127
Trieste Italy
Core-Electron Excitations in Dibenzothiophene
Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
P3
Baiano C
Department of Chemical Sciences
University of Naples Federico II
Ab initio characterization of CO2 photoreduction
mechanism at CuFeO2 delafossite electrode
P4
Davide Accomasso
Department of Chemistry and
Industrial Chemistry University
of Pisa Italy
Seeking new materials for singlet fission
covalent dimers as an alternative to molecular crystals
P5
Henry Adenusi
Chemistry Department University
of Rome ldquoLa Sapienzardquo Italy
Proton transfer mechanisms in protic ionic liquids P6
Giorgia Beata
Dipartimento di Chimica
Universitagrave di Torino Via Giuria 7
I-10125 Torino Italy
CRYSPLOT a new tool to visualize physical and
chemical properties of crystalline solids
P7
Marco Pagliai
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave degli Studi di
Firenze via della Lastruccia 3
50019 Sesto Fiorentino (FI) Italy
Molecular dynamics simulations of zinc proteins a
new force field
P8
Eslam M Moustafa
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria I-87036 Aracavacta
di Rende (CS) Italy
Reduction of Pt(IV) anticancer drugs a DFT mechanistic
study
P9
Alessandro Landi
Dipartimento di Chimica e
Biologia Adolfo Zambelli
Universitagrave di Salerno Via
Giovanni Paolo II I-84084
Fisciano (SA) Italy
Rapid evaluation of dynamic disorder in organic
semiconductors
P10
Isabella Romeo
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende I-87036
Italy
De novo proteins Insights from the theoretical
investigations
P11
Marina
Macchiagodena
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave degli Studi di
Firenze Via della Lastruccia 3 I-
50019 Sesto Fiorentino Italy
Improved force fields for molecular dynamics
simulations of zinc proteins
P12
Marco Fusegrave
Scuola Normale Superiore Piazza
dei Cavalieri 7 56126 Pisa Italy
Computational simulation of vibrationally resolved
spectra for spin‐forbidden transitionsforbidden transitions
P13
Tiziana Marino
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende I-87036
Italy
De novo proteins Insights from the theoretical
investigations
P14
Matteo Capone
Universitagrave dellrsquoAquila Italia Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
P15
J FREGONI
Dipartimento di scienze Fisiche
Informatiche e Matematiche
University of Modena and Reggio
Emilia I-41125 Modena Italy
Manipulating azobenzene photoisomerization
through strong light-molecule coupling
P16
Irene Conti
Dipartimento di Chimica
Industriale ldquo Toso Montanarirdquo
Universita di Bologna Viale del
Risorgimento 4 I-40136 Bologna
Italy
Excitonic State evolution of DNA Stacked Thymines
Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
P17
Andrea Le Donne
Chemistry department University
of Rome ldquoLa Sapienzardquo Rome
Italy
Ionic Liquids and Proton Transfer A Computational
Study to Understand Dynamic Processes
P18
Franco Egidi
Scuola Normale Superiore 56126
Pisa Italy
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
P19
Arianna Massaro
Department of Chemical Science
University of Naples ldquoFederico
IIrdquo via Cintia 21 80126 Naples
Italy
Unveiling the role of structural features in Na insertion
mechanism at anatase surfaces new insights for Na-ion
batteries development
P20
Alessandro Landi
Dipartimento di Chimica e
Biologia Adolfo Zambelli
Universitagrave di Salerno Via
Giovanni Paolo II I-84084
Fisciano (SA) Italy
Hole Mobility in Organic Semiconductors A Second-
Order Cumulant Approach
P21
Mariagrazia Fortino
Universitagrave di Modena e Reggio
Emilia Modena 41125 Italy
On the Simulation of Vibrationally Resolved Electronic
Spectra of medium-size molecules the case of Styryl
Substituted BODIPYs
P22
Marco Medves Dipdi Scienze Chimiche e
Farmaceutiche Universitagrave di
Trieste
Theoretical Study on the Circular Dichroism of Chiral
Bimetallic Clusters Ag-Au
P23
Jonathan Campeggio
Universitagrave degli Studi di Padova DiTe2 Calcolo del tensore di diffusione per molecole
flessibili
P24
Edoardo Jun
Mattioli
Chemistry Department ldquoG
Ciamicianrdquo University of Bologna
Computational Investigation of Competitive
Reaction Mechanisms inside Carbon Nanotubes
P25
Sergio Rampino
SMART Laboratory Scuola
Normale Superiore Piazza dei
Cavalieri 7 56126 Pisa
Combined Orbital-spaceReal-space Analysis of
Chemical Bonding through Virtual Reality
P26
Josephine Alba Dipdi Chimica Universitagrave di
Roma La Sapienza
Efficient and Accurate Modelling of Conformational
Transitions in proteins comparison between two Src
kinase proteins
P27
Abstracts delle conferenze su invito
I1
Solving the Schroumldinger equation in a box wavepackets and continuum states
Piero Decleva
DSCF Universitarsquo di Trieste declevaunitsit
ABSTRACT
Nelle molecole gli stati elettronici piursquo bassi decadono esponenzialmente con unrsquoestensione spaziale molto limitata Questo non ersquo piursquo vero per
- Stati Rydberg con alti numeri quantici - Stati del continuo - Pacchetti generati da impulsi elettromagnetici molto intensi
In tal caso le basi LCAO costruite da GTO o STO risultano inadeguate e sono necessari approcci alternativi sia funzioni di base diverse sia uso di griglie numeriche Per lo studio del continuo elettronico abbiamo da tempo sviluppato un set basato sullrsquouso di B-spline [1] come funzioni radiali adoperate nel modo LCAO convenzionale che si ersquo dimostrato assai flessibile e accurato Queste forniscono unrsquoeccellente rappresentazione delle soluzioni dellrsquoequazione di Schroumldinger allrsquointerno di una sfera di raggio prefissato arbitrario Calcoli dei parametri di fotoionizzazione molecolare a livello DFT [2] o TDDFT [3] forniscono generalmente risultati in buon accordo con lrsquoesperimento anche per sistemi relativamente grandi e per un gran numero di osservabili di fotoionizzazione sezioni drsquourto distribuzioni angolari di molecole con orientazione fissa o casuale parametri non-dipolari effetti di interferenza e diffrazione parametri chirali Ersquo stata anche applicata a fotoionizzazione risolta nel tempo da stati eccitati in esperimenti pump-probe e alla generazione di pacchetti di cationi da impulsi ultraveloci Piursquo recentemente la base ersquo stata applicata al calcolo di pacchetti drsquoonda eccitati da impulsi laser in regime non perturbativo Durante lrsquoimpulso lrsquoescursione dellrsquoelettrone puorsquo raggiungere migliaia di unitarsquo atomiche ma lrsquoapproccio ersquo numericamente molto stabile e si presta bene all propagazione del pacchetto per risoluzione dellrsquoequazione temporale Ersquo stata considerata la ionizzazione totale in funzione dellrsquoorientazione del campo rispetto alla molecola [4] il calcolo dello spettro di elettroni risolto in energia ed angolo attraverso la proiezione sugli autostati del continuo la rivelazione di pacchetti elettronici coerenti in esperimenti pump-probe agli attosecondi [5] la generazione di armoniche alte (HHG) [6] Verranno illustrati alcuni risultati recenti e discusse le linee di sviluppo
REFERENCES
1 H Bachau E Cormier P Decleva J E Hansen and F Martin ldquoApplications of B-splines in Atomic and Molecular Physicsrdquo
Reports on Progress in Physics 64 1815 (2001)
2 D Toffoli M Stener G Fronzoni and P Decleva ldquoConvergenge of the Multicenter B-spline DFT approach for the continuumrdquo
Chem Phys 276 25 (2002)
3 M Stener G Fronzoni and P Decleva ldquoTime-dependent density-functional theory for molecular photoionization with
noniterative algorithm and multicenter B-spline basis set CS2 and C6H6 case studiesrdquoJ Chem Phys 122 (2005) 234301
4 S Petretti YV Vanne A Saenz A Castro and P Decleva ldquoAlignment-Dependent Ionization of N2 O2 and CO2 in Intense
Laser Fieldsrdquo Phys Rev Letters 104 (2010) 223001
5 M Ruberti P Decleva and V Averbukh ldquoMulti-channel dynamics and correlation-driven inter-channel couplings in high
harmonic generation spectra of aligned CO2 molecule ab initio Time Dependent B-spline ADC ab initio analysisrdquo Phys Chem
Chem Phys 20 (2018) 8311
6 E Plesiat M Lara-Astiaso P Decleva A Palacios and F Martin ldquoReal-time determination of ultrafast charge dynamics in
tetrafluoromethane from attosecond pump-probe photoelectron spectroscopyrdquo Chem Eur J 242018 xxx
I2
Mixed quantumclassical description of the effects of nuclear motion in electronic spectroscopy and ultrafast
photophysics
Fabrizio Santoro1
1 ICCOM-CNR Area della Ricerca del CNR di Pisa Italy 2 Affiliazione 2
fabriziosantoroiccomcnrit
ABSTRACT
Quantum nuclear effects can play a relevant role in determining the shape of electronic spectra and the fate of the photoexcited dynamics in molecular systems Recent advancements in fully quantum vibronic approaches for the computation of spectra [12] and in quantum-dynamical (QD) approaches like those provided by the MCTDH method [3-5] allow an efficient description of such effects even in large systems if they are rigid (harmonic) and in gas phase Flexible systems or systems embedded in solvents or in heterogenoeus media possibly establishing with them specific interactions represent a challenge for fully quantum treatments of nuclear motions Classical and semi-classical trajectory based approaches are very well suited to deal with these cases but they neglect quantum nuclear effects We believe that the development of wise mixed quantum classical (MQC) approaches may represent a suitable framework to overcome some of these present limitations In this contribution we present our recent work in this field In electronic spectroscopy we introduced mixed schemes that separate fast and slow degrees of freedom (DoF) on the grounds of an adiabatic approximation and treat the fast DoF at quantum level and the slow ones (including the solvent) at classical level The spectra are then naturally expressed as an average of vibronic spectra involving along the fast DoF over the distribution of the classical DoF [5-7] Extending these ideas to ultrafast photophysical processes we recently proposed a MQC approach to introduce environmental dynamical effects in QD simulations In its simplest version all the solute degrees of freedom are represented by a wavepacket moving according to nonadiabatic quantum dynamics while the motion of an explicit solvent model is described by an ensemble of classical trajectories The core idea of the method is to describe the mutual coupling of the solute and solvent dynamics within a mean-field framework In this way the Hamiltonians of both the quantum and classical subsystems contain time-dependent terms due to the interaction with the other subset and the quantum and classical equations of motions are solved simultaneously We will discuss the potentialities limitations and possible perspectives of these methods with a number of test applications
REFERENCES
1 Barone V WIREs Comput Mol Sci 2016 6 86-110 2 Santoro F Jacquemin D WIREs Comput Mol Sci 2016 6 460-486 3 Wang H Thoss M J Chem Phys 2003 119 1289minus1299 Vendrell O Meyer H-D J Chem Phys 2011 134 044135 4 Beck M H J ckle A Worth G A Meyer H-D Phys Rep 2000 324 1minus105 5 CerezoJ Avila F Prampolini G Santoro F J Chem Theory Comput 2015 11 5810ndash5825
6 Cerezo J Mazzeo G Longhi G Abbate S Santoro F J Phys Chem Lett 2016 7 4891‐4897 7 Cerezo J Aranda D Avila F Mazzeo G Longhi G Abbate S Santoro F Chirality 2018 30 730ndash743 8 Cerezo J Liu Y Lin N Zhao X Improta R Santoro F J Chem Theory Comput 201814 820ndash832
I3
Defective but effective the role of defects on the electrocatalytic performance of oxide-based materials
for energy conversion
Ana B Muntildeoz Garciacutea1
1 Dipartimento di Fisica ldquoEttore Pancinirdquo Universitagrave di Napoli Federico II
Comp Univ Monte S Angelo via Cintia 21 80126 Napoli (Italia)
anabelenmunozgarciauninait
ABSTRACT
Ab initio simulations play an increasingly important role in materials sciences In the energy conversion scenario computational modeling can elucidate with atomic resolution the subtle composition-structure-property relationships behind the performance of functional materials and complex interfaces In heterogeneous electrocatalysis the underlying bulk and surface chargemass transport events are often strongly dependent on the presenceabsence of structural defects Thus a deep knowledge of defect chemistry is key for understanding tuning and optimizing the properties of different catalysts In particular this contribution will report recent advances in the DFT-based characterization of the role of defects in strongly correlated oxides as electrodes in electrocatalytic devices Three case studies will be presented (i) a new triple-conducting oxide based on Sr2Fe15Mo05O6 perovskite with promising bifunctional catalytic activity towards oxygen reduction and evolution reactions [1-3] (ii) Fe-doped ZrO2 for low temperature PEMFCs [4] and (iii) CuFeO2 delafossite for CO2 photoreduction [5] In all these cases we will discuss how surface oxygen vacancies -boosted by aliovalent doping- can improve the electrode performance and change product selectivity In conclusion this contribution will highlight the merits of computationally driven materials discovery in the context of energy conversion devices pointing out the importance of the necessary interplay between theory and experiment
REFERENCES
1 ABMG D Bugaris M Pavone J P Hodges A Huq F Chen H-C zur Loye E A Carter J Am Chem Soc 134 6826 (2012) 2 ABMG M Pavone Chem Mater 28 490 (2016) 3 ABMG M Pavone J Mater Chem A 5 12735 (2017) 4 P Madkikar D Menga G Harzer T Mittermeier A Siebel F E Wagner M Merz S Schuppler P Nagel ABMG M Pavone H A Gasteiger M Piana Submitted 5 J Gu A Wuttig J W Krizan Y Hu Z M Detweller R J Cava A B Bocarsly J Phys Chem C 117 12415 (2013)
I4
Solvent dynamics and energy transfer a real time description
Anna Painelli Francesco Di Maiolo
Dipartimento SCVSA Universitagrave di Parma annapainelliuniprit
ABSTRACT
Energy dissipation and relaxation phenomena are crucial to describe the dynamics of excited states The interaction of a molecule with the environment (the bath) is pivotal in this respect bringing theoretical chemistry towards the field of open quantum systems Several strategies are available to quantitatively describe the system-bath interaction most often based on the dynamics of the reduced density matrix Vibrational degrees of freedom must be explicitly described to address internal conversion and the huge dimension of the resulting basis imposes dramatic approximations to the calculation Here we face the problem adopting an essential state model (ESM) description of the molecular systems ESMs proved successful in describing low-energy linear and non-linear optical spectra of several families of organic dyes in terms of a minimal number of electronic states coupled to few effective vibrational modes ESMs successfully account for polar solvation and for intermolecular interactions in molecular aggregates and in energy transfer systems (1 2 3)
Here we present a dynamical non-adiabatic model for Resonance Energy Transfer (RET) Specifically we consider two dyes an energy donor (D) and an energy acceptor (A) Each dye corresponds to a push-pull chromophore described in terms of two electronic states coupled to a single effective vibration Accounting for dissipation phenomena within the Redfield approach we follow the real time dynamics of RET from the excited D towards A (Fig1 left panel) Moreover a newly derived multistate Redfield-Smoluchowski equation is used to investigate how the dynamical disorder induced by polar solvation affects RET (Fig1 right panel)
REFERENCES
1 F Terenziani A Painelli PhysChemChemPhys 17 13074-81 (2015) 2 C Sissa et al Phys Chem Chem Phys 2011 13 12734ndash12744 3 S Sanyal et al PhysChemChemPhys 2017 19 24979
Fig 1 Resonance
Energy Transfer in real
time Left Non-
adiabatic QUOTE
dynamics
following impulsive
excitation of the energy
donor the adiabatic
potential energy
surfaces are shown for
reference Right
temporal evolution of
the population of the
excited energy acceptor
in a frozen and liquid
polar solvent
I5
Towards an accurate computational photochemistry and photobiology the paradigmatic case of vision
Marco Garavelli1
1 Dipartimento di Chimica Industriale ldquoToso Montanarirdquo Viale del Risorgimento 4 40136 Bologna Italy 2 Affiliazione 2
marcogaravelliuniboit
ABSTRACT
The use of the computer to simulate light induced events in photoactive molecular materials has given access to a detailed description of the molecular motions and mechanisms underlying the reactivity of organic and bio-organic chromophores Thus different computational strategies and tools can now be operated like a ―virtual spectrometer to characterize and understand the photoinduced molecular deformation and reactivity of a given dye allowing for an accurate description of photochemicalphotobiological processes and a rational of the corresponding photophysical properties including time-resolved spectroscopy
This contribution reviews recent advances in this field by presenting methodological developments and applications in modeling the photophysicalphotochemical properties of organic chromophores and complex photoactive molecular architectures Retinal systems and visual proteins will be presented as a paradigmatic case [12] Hybrid QMMM calculations will be shown to be an elective tool for modeling photoinduced events and dynamics including tuningcontrolling effects of the environment For this purpose our new implementation of a general hybrid QMMM approach that is able to integrate some specialized softwares and acts as a flexible computational environment eventually allowing for so far inaccessible calculations (eg non-adiabatic molecular dynamics of unprecedented accuracy on large molecular materials) will be illustrated The information collected by these studies can be exploited for the design of novel photoactive molecular and soft materials including a novel paradigm of electrochromism for applications in a new generation of color tunable displays and e-ink devices Finally our latest achievements in developing (and modeling) non-linear bi-dimensional electronic spectroscopy as a novel diagnostic tool for tracking structuraldynamical problems in complex environments (eg biologically relevant systems such as proteins and DNA) will be presented [34]
REFERENCES
1 D Polli et al Nature 467 (2010) 440 2 B Demoulin et al JPCL 8 (2017) 4407 3 I Rivalta et al PCCP 16 (2014) 16865 4 I Rivalta et al JPCB 118 (2014) 8396
I6
Modellizzazione in fase condensata ad alte pressioni
Gianni Cardini
Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave di Firenze email giannicardiniunifiit
ABSTRACT
La modellizzazione delle proprietagrave strutturali e dinamiche di sistemi in fase condensata dipende essenzialmente dalla corretta descrizione del potenziale di interazione intermolecolare In simulazioni di dinamica molecolare1 si ricorre di solito a modelli di potenziale semi empirici o a metodi ab initio12 nella maggior parte dei casi basati sulla teoria del funzionale della densitagrave (DFT) Nel caso di sistemi sottoposti ad alte pressioni diventa cruciale una corretta descrizione delle interazioni a corto raggio e modelli che consentano eventualmente la rottura e formazione di legami chimici Verranno presentati alcuni risultati di simulazioni di dinamica molecolare ab initio con il metodo Car Parrinello Le simulazioni ab initio su fasi condensate basate su sistemi periodici sono dispendiose e pertanto condotte per tempi brevi e su campioni molto piccoli Inoltre nel campo delle alte pressioni gli sperimentali sono soliti interpretare i dati spettroscopici in termini di proprietagrave di singola molecola e necessitano di una modellizzazione possibilmente veloce per interpretare le loro misure Questo puograve essere ottenuto ricorrendo al metodo XP-PCM proposto da Cammi et al3 che consente di ottenere risultati qualitativi effettuando calcoli in condizioni estreme di pressione su singola molecola
REFERENCES
7 MP Allen amp DJ Tildesley Computer Simulation of Liquids Oxford University Press Oxford UK 2017 8 DMarx and J Hutter Ab Initio Molecular Dynamics Cambridge University Press Cambridge UK 2009 9 R Cammi et al Chem Phys 344 (2008) 135 R Cammi et al J ChemPhys 137 (2012) 154112
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
Venerdigrave 21 Settembre Sessione 6 Chairman Emilia Sicilia
915-1000 Invited ndash Gianni Cardini
Modellizzazione in fase condensata ad alte pressioni
1000-1015 Fortuna Ponte ldquoComputational investigation of the platinum(IV) anticancer
prodrugs reduction mechanism by L-ascorbic acidrdquo
1015-1030 Laura Falivene ldquoTuning Proximal and Remote Steric Effects in the
Rationalization of Catalytic Behaviorrdquo
1030-1045 Eduardo Schiavo ldquoInvestigating photoelectrochemical properties of dye-electrode
interfaces with density functional embedding theoryrdquo
1045-1100 Tainah Dorina Marforio ldquoCarbon nanotubes (CNTS) as nano-reactors
regioselectivity and kinetics control for the bromination of N-phenylacetamide A
QMMM investigationrdquo
1100-1145 Coffee Break (Atrio edificio H3)
Sessione 7 Sessione premi e medaglie Nordio ndash del Re ndash Scrocco ndash Roetti
Chairman Vincenzo Barone
1145-1200 Premio del Re Francesco Avanzini ldquoThe Quantum Molecular Trajectoryrdquo
1200-1230 Premio Scrocco Francesco Muniz-Miranda
Studies on the optoelectronic properties of metal nanoclusters and complexes
1230-1300 Premio Roetti Lorenzo Maschio
Quantum chemistry of crystalline solids using a local basis set the CRYSTAL
and CRYSCOR codes
1300 Conclusioni
Conferenze su invito Nome DipartimentoIstituzione Titolo contributo n
Piero Decleva DSCF Universitagrave di Trieste
Solving the Schroumldinger equation in a box wavepackets
and continuum states
I1
Fabrizio Santoro
ICCOM-CNR Area della Ricerca
del CNR di Pisa
Mixed quantumclassical description of the effects of
nuclear motion in electronic spectroscopy and ultrafast
photophysics
I2
Ana B Muntildeoz
Garciacutea
Dipartimento di Fisica ldquoEttore
Pancinirdquo Universitagrave di Napoli
Federico II
Defective but effective the role of defects on the
electrocatalytic performance of oxide-based materials for
energy conversion
I3
Anna Painelli
Dipartimento SCVSA Universitagrave
di Parma
Solvent dynamics and energy transfer
a real time description
I4
Marco Garavelli
Dipartimento di Chimica
Industriale ldquoToso Montanarirdquo
Bologna
Towards an accurate computational photochemistry and
photobiology the paradigmatic case of vision
I5
Gianni Cardini
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave di Firenze
Modellizzazione in fase condensata ad alte pressioni I6
Premi
Nome DipartimentoIstituzione Titolo contributo premio
Lorenzo Maschio Dipartimento di Chimica
Universitagrave di Torino
Quantum chemistry of crystalline solids using a local
basis set the CRYSTAL and CRYSCOR codes
Roetti
Francesco Muniz-
Miranda
Gent Universiteit Belgieuml Studies on the optoelectronic properties of metal
nanoclusters and complexes
Scrocco
Francesco Avanzini Dipartimento di Scienze
Chimiche Universitagrave degli Studi
di Padova
The Quantum Molecular Trajectory del Re
Contributi Orali
Nome DipartimentoIstituzione Titolo contributo n
Sofia Canola
Dipartimento di Chimica ldquoG
Ciamicianrdquo University of
Bologna via F Selmi 2 Bologna
Italy
Vibrational and optical fingerprints of conjugated
biradicals from DFT and TDDFT calculations
O1
Marco
Mendolicchio
Scuola Normale Superiore I-
56126 Pisa Italy
New computational strategies for the calculation of
anharmonic force fields
O2
Loredana Edith
Daga
Diparimento di Chimica
Universitagrave di Torino
On Optimizing Gaussian Basis sets for Crystalline Solids O3
Emanuele Coccia
Dipartimento di Scienze
Chimiche Universitagrave di Padova
via Marzolo 1 Padova Italy
Wave function-based approach to probe coherence in
ultrafast molecular processes
O4
Amalia Velardo
Dipartimento Chimica e Biologia
ldquoAdolfo Zambellirdquo Universitagrave
degli Studi di Salerno Via G
Paolo II 84084-Fisciano Italy
Band Shapes of Singlet-Triplet Transitions
O5
Laura Zanetti-Polzi
Department of Physical and
Chemical Sciences University of
LAquila Via Vetoio (Coppito1)
67010 LAquila Italy
Modeling amide I infrared spectra of proteins insights
from a perturbative approach
O6
Mario Prejanograve
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende (CS) Italia
The effect of distortions of a covalent enzymatic
intermediate in Human Transketolase a computational
point of view
O7
F Sessa
Department of Chemistry
University of Rome ldquoLa
Sapienzardquo Rome Italy
La3+ ion in EAN aqueous mixtures a MD-XAS
investigation on the effect of water concentration
O8
Diego Cesario
- Department of Chemistry and
Pharmaceutical Sciences and
Amsterdam Center for Multiscale
Modeling Vrije Universiteit
Amsterdam De Boelelaan 1083
1081 HV Amsterdam The
Netherlands
- Department of Chemistry
Biology and Biotechnology
University of Perugia
via Elce di Sotto 8 I-06123
Perugia Italy
Source of Cooperativity in Hydrogen-Bonded
Supramolecular Polymers
O9
Gloria Mazzone Chimie ParisTech PSL Research
University CNRS Institut de
Recherche de Chimie Paris Paris
France
Aiming at Color Prediction of Flexible Dyes in Aqueous
Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
O10
Michele Guerrini
Dipartimento FIM Universitagrave di
Modena e Reggio Emilia Italy
Solid-state effects on the optical excitation of push-pull
molecular J-aggregates by first principles simulations
O11
Mirco Zerbetto
Dipartimento di Scienze
Chimiche Universitagrave degli Studi
di Padova Padova 35313 Italia
Previsione dei Tempi di Rilassamento NMR di Molecole
Flessibili Oligosaccaridi come Caso di Studio
O12
F Faglioni
DSCG Univ of Modena and
Reggio Emilia Modena Italy
Self interaction charge delocalization electrolyte
ionization
O13
Mattia Anzola
Dipartimento di Scienze
Chimiche della Vita e della
Sostenibilitagrave Ambientale
Universitagrave degli Studi di Parma
Italy
Optical spectra of molecular aggregates testing
approximation schemes
O14
Martina De Vetta
-Institute of Theoretical
Chemistry Faculty of Chemistry
University of Vienna Waumlhringer
Str 17 A-1090 Vienna Austria
-Departamento de u mica
Universidad Aut noma de Madrid
Francisco Tomaacutes y Valiente 7
28049 Cantoblanco Madrid Spain
Simulations of a liposomal assisted delivery of the
Temoporfin photosensitizer
O15
Matteo Masetti Department of Pharmacy and
Biotechnology (FaBiT) Alma
Mater Studiorum ndash University of
Bologna Italy
The best of both worlds combining Markov State Models
and Path Collective Variables to describe protein-ligand
binding
O16
Ida Ritacco
CNR-IOM co SISSA via
Bonomea 265 34136 Trieste Italy
The mechanism of post-translation regulation of estrogen
biosynthesis in Breast cancer cells as revealed by atomic
level multiscale simulations
O17
Tommaso
Giovannini
Scuola Normale Superiore Piazza
dei Cavalieri 7 Pisa IT
Development of Theoretical Approaches to Model the
Spectral Properties of Complex Systems
O18
Fortuna Ponte
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria
Computational investigation of the platinum(IV)
anticancer prodrugs reduction mechanism by L-ascorbic
acid
O19
Laura Falivene
KAUST Catalysis Center King
Abdullah University of Science
and Technology Thuwal 23955-
6900 Saudi Arabia
Tuning Proximal and Remote Steric Effects in the
Rationalization of Catalytic Behavior
O20
E Schiavo
Department of Chemical Sciences
University of Naples Federico II
Comp Univ Monte SantrsquoAngelo
Via Cintia 21 80126 Naples Italy
Investigating photoelectrochemical properties of dye-
electrode interfaces with density functional embedding
theory
O21
Tainah Dorina
Marforio
Dipartimento di Chimica ldquoG
Ciamicianrdquo Alma Mater
Studiorum ndash Universitagrave di
Bologna via Selmi 2 40126
Bologna
Italy
CARBON NANOTUBES (CNTS) AS NANO-
REACTORS
REGIOSELECTIVITY AND KINETICS CONTROL
FOR
THE BROMINATION OF N-PHENYLACETAMIDE
A QMMM INVESTIGATION
O22
Poster Nome DipartimentoIstituzione Titolo contributo n
F Cappelluti
Universitagrave degli Studi dellrsquoAquila
- LrsquoAquila
F-RESP a fast and accurate polarizable force field P1
Francesco Tavanti
Department of Chemical and
Geological Sciences University of
Modena and Reggio Emilia Via
Campi 103 41125
Modena Italy
Natural compounds for Alzheimerrsquos disease treatment a
classical
Molecular Dynamics investigation
P2
E Bernes
Department of Chemical and
Pharmaceutical Sciences
University of Trieste 34127
Trieste Italy
Core-Electron Excitations in Dibenzothiophene
Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
P3
Baiano C
Department of Chemical Sciences
University of Naples Federico II
Ab initio characterization of CO2 photoreduction
mechanism at CuFeO2 delafossite electrode
P4
Davide Accomasso
Department of Chemistry and
Industrial Chemistry University
of Pisa Italy
Seeking new materials for singlet fission
covalent dimers as an alternative to molecular crystals
P5
Henry Adenusi
Chemistry Department University
of Rome ldquoLa Sapienzardquo Italy
Proton transfer mechanisms in protic ionic liquids P6
Giorgia Beata
Dipartimento di Chimica
Universitagrave di Torino Via Giuria 7
I-10125 Torino Italy
CRYSPLOT a new tool to visualize physical and
chemical properties of crystalline solids
P7
Marco Pagliai
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave degli Studi di
Firenze via della Lastruccia 3
50019 Sesto Fiorentino (FI) Italy
Molecular dynamics simulations of zinc proteins a
new force field
P8
Eslam M Moustafa
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria I-87036 Aracavacta
di Rende (CS) Italy
Reduction of Pt(IV) anticancer drugs a DFT mechanistic
study
P9
Alessandro Landi
Dipartimento di Chimica e
Biologia Adolfo Zambelli
Universitagrave di Salerno Via
Giovanni Paolo II I-84084
Fisciano (SA) Italy
Rapid evaluation of dynamic disorder in organic
semiconductors
P10
Isabella Romeo
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende I-87036
Italy
De novo proteins Insights from the theoretical
investigations
P11
Marina
Macchiagodena
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave degli Studi di
Firenze Via della Lastruccia 3 I-
50019 Sesto Fiorentino Italy
Improved force fields for molecular dynamics
simulations of zinc proteins
P12
Marco Fusegrave
Scuola Normale Superiore Piazza
dei Cavalieri 7 56126 Pisa Italy
Computational simulation of vibrationally resolved
spectra for spin‐forbidden transitionsforbidden transitions
P13
Tiziana Marino
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende I-87036
Italy
De novo proteins Insights from the theoretical
investigations
P14
Matteo Capone
Universitagrave dellrsquoAquila Italia Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
P15
J FREGONI
Dipartimento di scienze Fisiche
Informatiche e Matematiche
University of Modena and Reggio
Emilia I-41125 Modena Italy
Manipulating azobenzene photoisomerization
through strong light-molecule coupling
P16
Irene Conti
Dipartimento di Chimica
Industriale ldquo Toso Montanarirdquo
Universita di Bologna Viale del
Risorgimento 4 I-40136 Bologna
Italy
Excitonic State evolution of DNA Stacked Thymines
Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
P17
Andrea Le Donne
Chemistry department University
of Rome ldquoLa Sapienzardquo Rome
Italy
Ionic Liquids and Proton Transfer A Computational
Study to Understand Dynamic Processes
P18
Franco Egidi
Scuola Normale Superiore 56126
Pisa Italy
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
P19
Arianna Massaro
Department of Chemical Science
University of Naples ldquoFederico
IIrdquo via Cintia 21 80126 Naples
Italy
Unveiling the role of structural features in Na insertion
mechanism at anatase surfaces new insights for Na-ion
batteries development
P20
Alessandro Landi
Dipartimento di Chimica e
Biologia Adolfo Zambelli
Universitagrave di Salerno Via
Giovanni Paolo II I-84084
Fisciano (SA) Italy
Hole Mobility in Organic Semiconductors A Second-
Order Cumulant Approach
P21
Mariagrazia Fortino
Universitagrave di Modena e Reggio
Emilia Modena 41125 Italy
On the Simulation of Vibrationally Resolved Electronic
Spectra of medium-size molecules the case of Styryl
Substituted BODIPYs
P22
Marco Medves Dipdi Scienze Chimiche e
Farmaceutiche Universitagrave di
Trieste
Theoretical Study on the Circular Dichroism of Chiral
Bimetallic Clusters Ag-Au
P23
Jonathan Campeggio
Universitagrave degli Studi di Padova DiTe2 Calcolo del tensore di diffusione per molecole
flessibili
P24
Edoardo Jun
Mattioli
Chemistry Department ldquoG
Ciamicianrdquo University of Bologna
Computational Investigation of Competitive
Reaction Mechanisms inside Carbon Nanotubes
P25
Sergio Rampino
SMART Laboratory Scuola
Normale Superiore Piazza dei
Cavalieri 7 56126 Pisa
Combined Orbital-spaceReal-space Analysis of
Chemical Bonding through Virtual Reality
P26
Josephine Alba Dipdi Chimica Universitagrave di
Roma La Sapienza
Efficient and Accurate Modelling of Conformational
Transitions in proteins comparison between two Src
kinase proteins
P27
Abstracts delle conferenze su invito
I1
Solving the Schroumldinger equation in a box wavepackets and continuum states
Piero Decleva
DSCF Universitarsquo di Trieste declevaunitsit
ABSTRACT
Nelle molecole gli stati elettronici piursquo bassi decadono esponenzialmente con unrsquoestensione spaziale molto limitata Questo non ersquo piursquo vero per
- Stati Rydberg con alti numeri quantici - Stati del continuo - Pacchetti generati da impulsi elettromagnetici molto intensi
In tal caso le basi LCAO costruite da GTO o STO risultano inadeguate e sono necessari approcci alternativi sia funzioni di base diverse sia uso di griglie numeriche Per lo studio del continuo elettronico abbiamo da tempo sviluppato un set basato sullrsquouso di B-spline [1] come funzioni radiali adoperate nel modo LCAO convenzionale che si ersquo dimostrato assai flessibile e accurato Queste forniscono unrsquoeccellente rappresentazione delle soluzioni dellrsquoequazione di Schroumldinger allrsquointerno di una sfera di raggio prefissato arbitrario Calcoli dei parametri di fotoionizzazione molecolare a livello DFT [2] o TDDFT [3] forniscono generalmente risultati in buon accordo con lrsquoesperimento anche per sistemi relativamente grandi e per un gran numero di osservabili di fotoionizzazione sezioni drsquourto distribuzioni angolari di molecole con orientazione fissa o casuale parametri non-dipolari effetti di interferenza e diffrazione parametri chirali Ersquo stata anche applicata a fotoionizzazione risolta nel tempo da stati eccitati in esperimenti pump-probe e alla generazione di pacchetti di cationi da impulsi ultraveloci Piursquo recentemente la base ersquo stata applicata al calcolo di pacchetti drsquoonda eccitati da impulsi laser in regime non perturbativo Durante lrsquoimpulso lrsquoescursione dellrsquoelettrone puorsquo raggiungere migliaia di unitarsquo atomiche ma lrsquoapproccio ersquo numericamente molto stabile e si presta bene all propagazione del pacchetto per risoluzione dellrsquoequazione temporale Ersquo stata considerata la ionizzazione totale in funzione dellrsquoorientazione del campo rispetto alla molecola [4] il calcolo dello spettro di elettroni risolto in energia ed angolo attraverso la proiezione sugli autostati del continuo la rivelazione di pacchetti elettronici coerenti in esperimenti pump-probe agli attosecondi [5] la generazione di armoniche alte (HHG) [6] Verranno illustrati alcuni risultati recenti e discusse le linee di sviluppo
REFERENCES
1 H Bachau E Cormier P Decleva J E Hansen and F Martin ldquoApplications of B-splines in Atomic and Molecular Physicsrdquo
Reports on Progress in Physics 64 1815 (2001)
2 D Toffoli M Stener G Fronzoni and P Decleva ldquoConvergenge of the Multicenter B-spline DFT approach for the continuumrdquo
Chem Phys 276 25 (2002)
3 M Stener G Fronzoni and P Decleva ldquoTime-dependent density-functional theory for molecular photoionization with
noniterative algorithm and multicenter B-spline basis set CS2 and C6H6 case studiesrdquoJ Chem Phys 122 (2005) 234301
4 S Petretti YV Vanne A Saenz A Castro and P Decleva ldquoAlignment-Dependent Ionization of N2 O2 and CO2 in Intense
Laser Fieldsrdquo Phys Rev Letters 104 (2010) 223001
5 M Ruberti P Decleva and V Averbukh ldquoMulti-channel dynamics and correlation-driven inter-channel couplings in high
harmonic generation spectra of aligned CO2 molecule ab initio Time Dependent B-spline ADC ab initio analysisrdquo Phys Chem
Chem Phys 20 (2018) 8311
6 E Plesiat M Lara-Astiaso P Decleva A Palacios and F Martin ldquoReal-time determination of ultrafast charge dynamics in
tetrafluoromethane from attosecond pump-probe photoelectron spectroscopyrdquo Chem Eur J 242018 xxx
I2
Mixed quantumclassical description of the effects of nuclear motion in electronic spectroscopy and ultrafast
photophysics
Fabrizio Santoro1
1 ICCOM-CNR Area della Ricerca del CNR di Pisa Italy 2 Affiliazione 2
fabriziosantoroiccomcnrit
ABSTRACT
Quantum nuclear effects can play a relevant role in determining the shape of electronic spectra and the fate of the photoexcited dynamics in molecular systems Recent advancements in fully quantum vibronic approaches for the computation of spectra [12] and in quantum-dynamical (QD) approaches like those provided by the MCTDH method [3-5] allow an efficient description of such effects even in large systems if they are rigid (harmonic) and in gas phase Flexible systems or systems embedded in solvents or in heterogenoeus media possibly establishing with them specific interactions represent a challenge for fully quantum treatments of nuclear motions Classical and semi-classical trajectory based approaches are very well suited to deal with these cases but they neglect quantum nuclear effects We believe that the development of wise mixed quantum classical (MQC) approaches may represent a suitable framework to overcome some of these present limitations In this contribution we present our recent work in this field In electronic spectroscopy we introduced mixed schemes that separate fast and slow degrees of freedom (DoF) on the grounds of an adiabatic approximation and treat the fast DoF at quantum level and the slow ones (including the solvent) at classical level The spectra are then naturally expressed as an average of vibronic spectra involving along the fast DoF over the distribution of the classical DoF [5-7] Extending these ideas to ultrafast photophysical processes we recently proposed a MQC approach to introduce environmental dynamical effects in QD simulations In its simplest version all the solute degrees of freedom are represented by a wavepacket moving according to nonadiabatic quantum dynamics while the motion of an explicit solvent model is described by an ensemble of classical trajectories The core idea of the method is to describe the mutual coupling of the solute and solvent dynamics within a mean-field framework In this way the Hamiltonians of both the quantum and classical subsystems contain time-dependent terms due to the interaction with the other subset and the quantum and classical equations of motions are solved simultaneously We will discuss the potentialities limitations and possible perspectives of these methods with a number of test applications
REFERENCES
1 Barone V WIREs Comput Mol Sci 2016 6 86-110 2 Santoro F Jacquemin D WIREs Comput Mol Sci 2016 6 460-486 3 Wang H Thoss M J Chem Phys 2003 119 1289minus1299 Vendrell O Meyer H-D J Chem Phys 2011 134 044135 4 Beck M H J ckle A Worth G A Meyer H-D Phys Rep 2000 324 1minus105 5 CerezoJ Avila F Prampolini G Santoro F J Chem Theory Comput 2015 11 5810ndash5825
6 Cerezo J Mazzeo G Longhi G Abbate S Santoro F J Phys Chem Lett 2016 7 4891‐4897 7 Cerezo J Aranda D Avila F Mazzeo G Longhi G Abbate S Santoro F Chirality 2018 30 730ndash743 8 Cerezo J Liu Y Lin N Zhao X Improta R Santoro F J Chem Theory Comput 201814 820ndash832
I3
Defective but effective the role of defects on the electrocatalytic performance of oxide-based materials
for energy conversion
Ana B Muntildeoz Garciacutea1
1 Dipartimento di Fisica ldquoEttore Pancinirdquo Universitagrave di Napoli Federico II
Comp Univ Monte S Angelo via Cintia 21 80126 Napoli (Italia)
anabelenmunozgarciauninait
ABSTRACT
Ab initio simulations play an increasingly important role in materials sciences In the energy conversion scenario computational modeling can elucidate with atomic resolution the subtle composition-structure-property relationships behind the performance of functional materials and complex interfaces In heterogeneous electrocatalysis the underlying bulk and surface chargemass transport events are often strongly dependent on the presenceabsence of structural defects Thus a deep knowledge of defect chemistry is key for understanding tuning and optimizing the properties of different catalysts In particular this contribution will report recent advances in the DFT-based characterization of the role of defects in strongly correlated oxides as electrodes in electrocatalytic devices Three case studies will be presented (i) a new triple-conducting oxide based on Sr2Fe15Mo05O6 perovskite with promising bifunctional catalytic activity towards oxygen reduction and evolution reactions [1-3] (ii) Fe-doped ZrO2 for low temperature PEMFCs [4] and (iii) CuFeO2 delafossite for CO2 photoreduction [5] In all these cases we will discuss how surface oxygen vacancies -boosted by aliovalent doping- can improve the electrode performance and change product selectivity In conclusion this contribution will highlight the merits of computationally driven materials discovery in the context of energy conversion devices pointing out the importance of the necessary interplay between theory and experiment
REFERENCES
1 ABMG D Bugaris M Pavone J P Hodges A Huq F Chen H-C zur Loye E A Carter J Am Chem Soc 134 6826 (2012) 2 ABMG M Pavone Chem Mater 28 490 (2016) 3 ABMG M Pavone J Mater Chem A 5 12735 (2017) 4 P Madkikar D Menga G Harzer T Mittermeier A Siebel F E Wagner M Merz S Schuppler P Nagel ABMG M Pavone H A Gasteiger M Piana Submitted 5 J Gu A Wuttig J W Krizan Y Hu Z M Detweller R J Cava A B Bocarsly J Phys Chem C 117 12415 (2013)
I4
Solvent dynamics and energy transfer a real time description
Anna Painelli Francesco Di Maiolo
Dipartimento SCVSA Universitagrave di Parma annapainelliuniprit
ABSTRACT
Energy dissipation and relaxation phenomena are crucial to describe the dynamics of excited states The interaction of a molecule with the environment (the bath) is pivotal in this respect bringing theoretical chemistry towards the field of open quantum systems Several strategies are available to quantitatively describe the system-bath interaction most often based on the dynamics of the reduced density matrix Vibrational degrees of freedom must be explicitly described to address internal conversion and the huge dimension of the resulting basis imposes dramatic approximations to the calculation Here we face the problem adopting an essential state model (ESM) description of the molecular systems ESMs proved successful in describing low-energy linear and non-linear optical spectra of several families of organic dyes in terms of a minimal number of electronic states coupled to few effective vibrational modes ESMs successfully account for polar solvation and for intermolecular interactions in molecular aggregates and in energy transfer systems (1 2 3)
Here we present a dynamical non-adiabatic model for Resonance Energy Transfer (RET) Specifically we consider two dyes an energy donor (D) and an energy acceptor (A) Each dye corresponds to a push-pull chromophore described in terms of two electronic states coupled to a single effective vibration Accounting for dissipation phenomena within the Redfield approach we follow the real time dynamics of RET from the excited D towards A (Fig1 left panel) Moreover a newly derived multistate Redfield-Smoluchowski equation is used to investigate how the dynamical disorder induced by polar solvation affects RET (Fig1 right panel)
REFERENCES
1 F Terenziani A Painelli PhysChemChemPhys 17 13074-81 (2015) 2 C Sissa et al Phys Chem Chem Phys 2011 13 12734ndash12744 3 S Sanyal et al PhysChemChemPhys 2017 19 24979
Fig 1 Resonance
Energy Transfer in real
time Left Non-
adiabatic QUOTE
dynamics
following impulsive
excitation of the energy
donor the adiabatic
potential energy
surfaces are shown for
reference Right
temporal evolution of
the population of the
excited energy acceptor
in a frozen and liquid
polar solvent
I5
Towards an accurate computational photochemistry and photobiology the paradigmatic case of vision
Marco Garavelli1
1 Dipartimento di Chimica Industriale ldquoToso Montanarirdquo Viale del Risorgimento 4 40136 Bologna Italy 2 Affiliazione 2
marcogaravelliuniboit
ABSTRACT
The use of the computer to simulate light induced events in photoactive molecular materials has given access to a detailed description of the molecular motions and mechanisms underlying the reactivity of organic and bio-organic chromophores Thus different computational strategies and tools can now be operated like a ―virtual spectrometer to characterize and understand the photoinduced molecular deformation and reactivity of a given dye allowing for an accurate description of photochemicalphotobiological processes and a rational of the corresponding photophysical properties including time-resolved spectroscopy
This contribution reviews recent advances in this field by presenting methodological developments and applications in modeling the photophysicalphotochemical properties of organic chromophores and complex photoactive molecular architectures Retinal systems and visual proteins will be presented as a paradigmatic case [12] Hybrid QMMM calculations will be shown to be an elective tool for modeling photoinduced events and dynamics including tuningcontrolling effects of the environment For this purpose our new implementation of a general hybrid QMMM approach that is able to integrate some specialized softwares and acts as a flexible computational environment eventually allowing for so far inaccessible calculations (eg non-adiabatic molecular dynamics of unprecedented accuracy on large molecular materials) will be illustrated The information collected by these studies can be exploited for the design of novel photoactive molecular and soft materials including a novel paradigm of electrochromism for applications in a new generation of color tunable displays and e-ink devices Finally our latest achievements in developing (and modeling) non-linear bi-dimensional electronic spectroscopy as a novel diagnostic tool for tracking structuraldynamical problems in complex environments (eg biologically relevant systems such as proteins and DNA) will be presented [34]
REFERENCES
1 D Polli et al Nature 467 (2010) 440 2 B Demoulin et al JPCL 8 (2017) 4407 3 I Rivalta et al PCCP 16 (2014) 16865 4 I Rivalta et al JPCB 118 (2014) 8396
I6
Modellizzazione in fase condensata ad alte pressioni
Gianni Cardini
Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave di Firenze email giannicardiniunifiit
ABSTRACT
La modellizzazione delle proprietagrave strutturali e dinamiche di sistemi in fase condensata dipende essenzialmente dalla corretta descrizione del potenziale di interazione intermolecolare In simulazioni di dinamica molecolare1 si ricorre di solito a modelli di potenziale semi empirici o a metodi ab initio12 nella maggior parte dei casi basati sulla teoria del funzionale della densitagrave (DFT) Nel caso di sistemi sottoposti ad alte pressioni diventa cruciale una corretta descrizione delle interazioni a corto raggio e modelli che consentano eventualmente la rottura e formazione di legami chimici Verranno presentati alcuni risultati di simulazioni di dinamica molecolare ab initio con il metodo Car Parrinello Le simulazioni ab initio su fasi condensate basate su sistemi periodici sono dispendiose e pertanto condotte per tempi brevi e su campioni molto piccoli Inoltre nel campo delle alte pressioni gli sperimentali sono soliti interpretare i dati spettroscopici in termini di proprietagrave di singola molecola e necessitano di una modellizzazione possibilmente veloce per interpretare le loro misure Questo puograve essere ottenuto ricorrendo al metodo XP-PCM proposto da Cammi et al3 che consente di ottenere risultati qualitativi effettuando calcoli in condizioni estreme di pressione su singola molecola
REFERENCES
7 MP Allen amp DJ Tildesley Computer Simulation of Liquids Oxford University Press Oxford UK 2017 8 DMarx and J Hutter Ab Initio Molecular Dynamics Cambridge University Press Cambridge UK 2009 9 R Cammi et al Chem Phys 344 (2008) 135 R Cammi et al J ChemPhys 137 (2012) 154112
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
Conferenze su invito Nome DipartimentoIstituzione Titolo contributo n
Piero Decleva DSCF Universitagrave di Trieste
Solving the Schroumldinger equation in a box wavepackets
and continuum states
I1
Fabrizio Santoro
ICCOM-CNR Area della Ricerca
del CNR di Pisa
Mixed quantumclassical description of the effects of
nuclear motion in electronic spectroscopy and ultrafast
photophysics
I2
Ana B Muntildeoz
Garciacutea
Dipartimento di Fisica ldquoEttore
Pancinirdquo Universitagrave di Napoli
Federico II
Defective but effective the role of defects on the
electrocatalytic performance of oxide-based materials for
energy conversion
I3
Anna Painelli
Dipartimento SCVSA Universitagrave
di Parma
Solvent dynamics and energy transfer
a real time description
I4
Marco Garavelli
Dipartimento di Chimica
Industriale ldquoToso Montanarirdquo
Bologna
Towards an accurate computational photochemistry and
photobiology the paradigmatic case of vision
I5
Gianni Cardini
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave di Firenze
Modellizzazione in fase condensata ad alte pressioni I6
Premi
Nome DipartimentoIstituzione Titolo contributo premio
Lorenzo Maschio Dipartimento di Chimica
Universitagrave di Torino
Quantum chemistry of crystalline solids using a local
basis set the CRYSTAL and CRYSCOR codes
Roetti
Francesco Muniz-
Miranda
Gent Universiteit Belgieuml Studies on the optoelectronic properties of metal
nanoclusters and complexes
Scrocco
Francesco Avanzini Dipartimento di Scienze
Chimiche Universitagrave degli Studi
di Padova
The Quantum Molecular Trajectory del Re
Contributi Orali
Nome DipartimentoIstituzione Titolo contributo n
Sofia Canola
Dipartimento di Chimica ldquoG
Ciamicianrdquo University of
Bologna via F Selmi 2 Bologna
Italy
Vibrational and optical fingerprints of conjugated
biradicals from DFT and TDDFT calculations
O1
Marco
Mendolicchio
Scuola Normale Superiore I-
56126 Pisa Italy
New computational strategies for the calculation of
anharmonic force fields
O2
Loredana Edith
Daga
Diparimento di Chimica
Universitagrave di Torino
On Optimizing Gaussian Basis sets for Crystalline Solids O3
Emanuele Coccia
Dipartimento di Scienze
Chimiche Universitagrave di Padova
via Marzolo 1 Padova Italy
Wave function-based approach to probe coherence in
ultrafast molecular processes
O4
Amalia Velardo
Dipartimento Chimica e Biologia
ldquoAdolfo Zambellirdquo Universitagrave
degli Studi di Salerno Via G
Paolo II 84084-Fisciano Italy
Band Shapes of Singlet-Triplet Transitions
O5
Laura Zanetti-Polzi
Department of Physical and
Chemical Sciences University of
LAquila Via Vetoio (Coppito1)
67010 LAquila Italy
Modeling amide I infrared spectra of proteins insights
from a perturbative approach
O6
Mario Prejanograve
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende (CS) Italia
The effect of distortions of a covalent enzymatic
intermediate in Human Transketolase a computational
point of view
O7
F Sessa
Department of Chemistry
University of Rome ldquoLa
Sapienzardquo Rome Italy
La3+ ion in EAN aqueous mixtures a MD-XAS
investigation on the effect of water concentration
O8
Diego Cesario
- Department of Chemistry and
Pharmaceutical Sciences and
Amsterdam Center for Multiscale
Modeling Vrije Universiteit
Amsterdam De Boelelaan 1083
1081 HV Amsterdam The
Netherlands
- Department of Chemistry
Biology and Biotechnology
University of Perugia
via Elce di Sotto 8 I-06123
Perugia Italy
Source of Cooperativity in Hydrogen-Bonded
Supramolecular Polymers
O9
Gloria Mazzone Chimie ParisTech PSL Research
University CNRS Institut de
Recherche de Chimie Paris Paris
France
Aiming at Color Prediction of Flexible Dyes in Aqueous
Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
O10
Michele Guerrini
Dipartimento FIM Universitagrave di
Modena e Reggio Emilia Italy
Solid-state effects on the optical excitation of push-pull
molecular J-aggregates by first principles simulations
O11
Mirco Zerbetto
Dipartimento di Scienze
Chimiche Universitagrave degli Studi
di Padova Padova 35313 Italia
Previsione dei Tempi di Rilassamento NMR di Molecole
Flessibili Oligosaccaridi come Caso di Studio
O12
F Faglioni
DSCG Univ of Modena and
Reggio Emilia Modena Italy
Self interaction charge delocalization electrolyte
ionization
O13
Mattia Anzola
Dipartimento di Scienze
Chimiche della Vita e della
Sostenibilitagrave Ambientale
Universitagrave degli Studi di Parma
Italy
Optical spectra of molecular aggregates testing
approximation schemes
O14
Martina De Vetta
-Institute of Theoretical
Chemistry Faculty of Chemistry
University of Vienna Waumlhringer
Str 17 A-1090 Vienna Austria
-Departamento de u mica
Universidad Aut noma de Madrid
Francisco Tomaacutes y Valiente 7
28049 Cantoblanco Madrid Spain
Simulations of a liposomal assisted delivery of the
Temoporfin photosensitizer
O15
Matteo Masetti Department of Pharmacy and
Biotechnology (FaBiT) Alma
Mater Studiorum ndash University of
Bologna Italy
The best of both worlds combining Markov State Models
and Path Collective Variables to describe protein-ligand
binding
O16
Ida Ritacco
CNR-IOM co SISSA via
Bonomea 265 34136 Trieste Italy
The mechanism of post-translation regulation of estrogen
biosynthesis in Breast cancer cells as revealed by atomic
level multiscale simulations
O17
Tommaso
Giovannini
Scuola Normale Superiore Piazza
dei Cavalieri 7 Pisa IT
Development of Theoretical Approaches to Model the
Spectral Properties of Complex Systems
O18
Fortuna Ponte
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria
Computational investigation of the platinum(IV)
anticancer prodrugs reduction mechanism by L-ascorbic
acid
O19
Laura Falivene
KAUST Catalysis Center King
Abdullah University of Science
and Technology Thuwal 23955-
6900 Saudi Arabia
Tuning Proximal and Remote Steric Effects in the
Rationalization of Catalytic Behavior
O20
E Schiavo
Department of Chemical Sciences
University of Naples Federico II
Comp Univ Monte SantrsquoAngelo
Via Cintia 21 80126 Naples Italy
Investigating photoelectrochemical properties of dye-
electrode interfaces with density functional embedding
theory
O21
Tainah Dorina
Marforio
Dipartimento di Chimica ldquoG
Ciamicianrdquo Alma Mater
Studiorum ndash Universitagrave di
Bologna via Selmi 2 40126
Bologna
Italy
CARBON NANOTUBES (CNTS) AS NANO-
REACTORS
REGIOSELECTIVITY AND KINETICS CONTROL
FOR
THE BROMINATION OF N-PHENYLACETAMIDE
A QMMM INVESTIGATION
O22
Poster Nome DipartimentoIstituzione Titolo contributo n
F Cappelluti
Universitagrave degli Studi dellrsquoAquila
- LrsquoAquila
F-RESP a fast and accurate polarizable force field P1
Francesco Tavanti
Department of Chemical and
Geological Sciences University of
Modena and Reggio Emilia Via
Campi 103 41125
Modena Italy
Natural compounds for Alzheimerrsquos disease treatment a
classical
Molecular Dynamics investigation
P2
E Bernes
Department of Chemical and
Pharmaceutical Sciences
University of Trieste 34127
Trieste Italy
Core-Electron Excitations in Dibenzothiophene
Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
P3
Baiano C
Department of Chemical Sciences
University of Naples Federico II
Ab initio characterization of CO2 photoreduction
mechanism at CuFeO2 delafossite electrode
P4
Davide Accomasso
Department of Chemistry and
Industrial Chemistry University
of Pisa Italy
Seeking new materials for singlet fission
covalent dimers as an alternative to molecular crystals
P5
Henry Adenusi
Chemistry Department University
of Rome ldquoLa Sapienzardquo Italy
Proton transfer mechanisms in protic ionic liquids P6
Giorgia Beata
Dipartimento di Chimica
Universitagrave di Torino Via Giuria 7
I-10125 Torino Italy
CRYSPLOT a new tool to visualize physical and
chemical properties of crystalline solids
P7
Marco Pagliai
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave degli Studi di
Firenze via della Lastruccia 3
50019 Sesto Fiorentino (FI) Italy
Molecular dynamics simulations of zinc proteins a
new force field
P8
Eslam M Moustafa
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria I-87036 Aracavacta
di Rende (CS) Italy
Reduction of Pt(IV) anticancer drugs a DFT mechanistic
study
P9
Alessandro Landi
Dipartimento di Chimica e
Biologia Adolfo Zambelli
Universitagrave di Salerno Via
Giovanni Paolo II I-84084
Fisciano (SA) Italy
Rapid evaluation of dynamic disorder in organic
semiconductors
P10
Isabella Romeo
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende I-87036
Italy
De novo proteins Insights from the theoretical
investigations
P11
Marina
Macchiagodena
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave degli Studi di
Firenze Via della Lastruccia 3 I-
50019 Sesto Fiorentino Italy
Improved force fields for molecular dynamics
simulations of zinc proteins
P12
Marco Fusegrave
Scuola Normale Superiore Piazza
dei Cavalieri 7 56126 Pisa Italy
Computational simulation of vibrationally resolved
spectra for spin‐forbidden transitionsforbidden transitions
P13
Tiziana Marino
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende I-87036
Italy
De novo proteins Insights from the theoretical
investigations
P14
Matteo Capone
Universitagrave dellrsquoAquila Italia Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
P15
J FREGONI
Dipartimento di scienze Fisiche
Informatiche e Matematiche
University of Modena and Reggio
Emilia I-41125 Modena Italy
Manipulating azobenzene photoisomerization
through strong light-molecule coupling
P16
Irene Conti
Dipartimento di Chimica
Industriale ldquo Toso Montanarirdquo
Universita di Bologna Viale del
Risorgimento 4 I-40136 Bologna
Italy
Excitonic State evolution of DNA Stacked Thymines
Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
P17
Andrea Le Donne
Chemistry department University
of Rome ldquoLa Sapienzardquo Rome
Italy
Ionic Liquids and Proton Transfer A Computational
Study to Understand Dynamic Processes
P18
Franco Egidi
Scuola Normale Superiore 56126
Pisa Italy
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
P19
Arianna Massaro
Department of Chemical Science
University of Naples ldquoFederico
IIrdquo via Cintia 21 80126 Naples
Italy
Unveiling the role of structural features in Na insertion
mechanism at anatase surfaces new insights for Na-ion
batteries development
P20
Alessandro Landi
Dipartimento di Chimica e
Biologia Adolfo Zambelli
Universitagrave di Salerno Via
Giovanni Paolo II I-84084
Fisciano (SA) Italy
Hole Mobility in Organic Semiconductors A Second-
Order Cumulant Approach
P21
Mariagrazia Fortino
Universitagrave di Modena e Reggio
Emilia Modena 41125 Italy
On the Simulation of Vibrationally Resolved Electronic
Spectra of medium-size molecules the case of Styryl
Substituted BODIPYs
P22
Marco Medves Dipdi Scienze Chimiche e
Farmaceutiche Universitagrave di
Trieste
Theoretical Study on the Circular Dichroism of Chiral
Bimetallic Clusters Ag-Au
P23
Jonathan Campeggio
Universitagrave degli Studi di Padova DiTe2 Calcolo del tensore di diffusione per molecole
flessibili
P24
Edoardo Jun
Mattioli
Chemistry Department ldquoG
Ciamicianrdquo University of Bologna
Computational Investigation of Competitive
Reaction Mechanisms inside Carbon Nanotubes
P25
Sergio Rampino
SMART Laboratory Scuola
Normale Superiore Piazza dei
Cavalieri 7 56126 Pisa
Combined Orbital-spaceReal-space Analysis of
Chemical Bonding through Virtual Reality
P26
Josephine Alba Dipdi Chimica Universitagrave di
Roma La Sapienza
Efficient and Accurate Modelling of Conformational
Transitions in proteins comparison between two Src
kinase proteins
P27
Abstracts delle conferenze su invito
I1
Solving the Schroumldinger equation in a box wavepackets and continuum states
Piero Decleva
DSCF Universitarsquo di Trieste declevaunitsit
ABSTRACT
Nelle molecole gli stati elettronici piursquo bassi decadono esponenzialmente con unrsquoestensione spaziale molto limitata Questo non ersquo piursquo vero per
- Stati Rydberg con alti numeri quantici - Stati del continuo - Pacchetti generati da impulsi elettromagnetici molto intensi
In tal caso le basi LCAO costruite da GTO o STO risultano inadeguate e sono necessari approcci alternativi sia funzioni di base diverse sia uso di griglie numeriche Per lo studio del continuo elettronico abbiamo da tempo sviluppato un set basato sullrsquouso di B-spline [1] come funzioni radiali adoperate nel modo LCAO convenzionale che si ersquo dimostrato assai flessibile e accurato Queste forniscono unrsquoeccellente rappresentazione delle soluzioni dellrsquoequazione di Schroumldinger allrsquointerno di una sfera di raggio prefissato arbitrario Calcoli dei parametri di fotoionizzazione molecolare a livello DFT [2] o TDDFT [3] forniscono generalmente risultati in buon accordo con lrsquoesperimento anche per sistemi relativamente grandi e per un gran numero di osservabili di fotoionizzazione sezioni drsquourto distribuzioni angolari di molecole con orientazione fissa o casuale parametri non-dipolari effetti di interferenza e diffrazione parametri chirali Ersquo stata anche applicata a fotoionizzazione risolta nel tempo da stati eccitati in esperimenti pump-probe e alla generazione di pacchetti di cationi da impulsi ultraveloci Piursquo recentemente la base ersquo stata applicata al calcolo di pacchetti drsquoonda eccitati da impulsi laser in regime non perturbativo Durante lrsquoimpulso lrsquoescursione dellrsquoelettrone puorsquo raggiungere migliaia di unitarsquo atomiche ma lrsquoapproccio ersquo numericamente molto stabile e si presta bene all propagazione del pacchetto per risoluzione dellrsquoequazione temporale Ersquo stata considerata la ionizzazione totale in funzione dellrsquoorientazione del campo rispetto alla molecola [4] il calcolo dello spettro di elettroni risolto in energia ed angolo attraverso la proiezione sugli autostati del continuo la rivelazione di pacchetti elettronici coerenti in esperimenti pump-probe agli attosecondi [5] la generazione di armoniche alte (HHG) [6] Verranno illustrati alcuni risultati recenti e discusse le linee di sviluppo
REFERENCES
1 H Bachau E Cormier P Decleva J E Hansen and F Martin ldquoApplications of B-splines in Atomic and Molecular Physicsrdquo
Reports on Progress in Physics 64 1815 (2001)
2 D Toffoli M Stener G Fronzoni and P Decleva ldquoConvergenge of the Multicenter B-spline DFT approach for the continuumrdquo
Chem Phys 276 25 (2002)
3 M Stener G Fronzoni and P Decleva ldquoTime-dependent density-functional theory for molecular photoionization with
noniterative algorithm and multicenter B-spline basis set CS2 and C6H6 case studiesrdquoJ Chem Phys 122 (2005) 234301
4 S Petretti YV Vanne A Saenz A Castro and P Decleva ldquoAlignment-Dependent Ionization of N2 O2 and CO2 in Intense
Laser Fieldsrdquo Phys Rev Letters 104 (2010) 223001
5 M Ruberti P Decleva and V Averbukh ldquoMulti-channel dynamics and correlation-driven inter-channel couplings in high
harmonic generation spectra of aligned CO2 molecule ab initio Time Dependent B-spline ADC ab initio analysisrdquo Phys Chem
Chem Phys 20 (2018) 8311
6 E Plesiat M Lara-Astiaso P Decleva A Palacios and F Martin ldquoReal-time determination of ultrafast charge dynamics in
tetrafluoromethane from attosecond pump-probe photoelectron spectroscopyrdquo Chem Eur J 242018 xxx
I2
Mixed quantumclassical description of the effects of nuclear motion in electronic spectroscopy and ultrafast
photophysics
Fabrizio Santoro1
1 ICCOM-CNR Area della Ricerca del CNR di Pisa Italy 2 Affiliazione 2
fabriziosantoroiccomcnrit
ABSTRACT
Quantum nuclear effects can play a relevant role in determining the shape of electronic spectra and the fate of the photoexcited dynamics in molecular systems Recent advancements in fully quantum vibronic approaches for the computation of spectra [12] and in quantum-dynamical (QD) approaches like those provided by the MCTDH method [3-5] allow an efficient description of such effects even in large systems if they are rigid (harmonic) and in gas phase Flexible systems or systems embedded in solvents or in heterogenoeus media possibly establishing with them specific interactions represent a challenge for fully quantum treatments of nuclear motions Classical and semi-classical trajectory based approaches are very well suited to deal with these cases but they neglect quantum nuclear effects We believe that the development of wise mixed quantum classical (MQC) approaches may represent a suitable framework to overcome some of these present limitations In this contribution we present our recent work in this field In electronic spectroscopy we introduced mixed schemes that separate fast and slow degrees of freedom (DoF) on the grounds of an adiabatic approximation and treat the fast DoF at quantum level and the slow ones (including the solvent) at classical level The spectra are then naturally expressed as an average of vibronic spectra involving along the fast DoF over the distribution of the classical DoF [5-7] Extending these ideas to ultrafast photophysical processes we recently proposed a MQC approach to introduce environmental dynamical effects in QD simulations In its simplest version all the solute degrees of freedom are represented by a wavepacket moving according to nonadiabatic quantum dynamics while the motion of an explicit solvent model is described by an ensemble of classical trajectories The core idea of the method is to describe the mutual coupling of the solute and solvent dynamics within a mean-field framework In this way the Hamiltonians of both the quantum and classical subsystems contain time-dependent terms due to the interaction with the other subset and the quantum and classical equations of motions are solved simultaneously We will discuss the potentialities limitations and possible perspectives of these methods with a number of test applications
REFERENCES
1 Barone V WIREs Comput Mol Sci 2016 6 86-110 2 Santoro F Jacquemin D WIREs Comput Mol Sci 2016 6 460-486 3 Wang H Thoss M J Chem Phys 2003 119 1289minus1299 Vendrell O Meyer H-D J Chem Phys 2011 134 044135 4 Beck M H J ckle A Worth G A Meyer H-D Phys Rep 2000 324 1minus105 5 CerezoJ Avila F Prampolini G Santoro F J Chem Theory Comput 2015 11 5810ndash5825
6 Cerezo J Mazzeo G Longhi G Abbate S Santoro F J Phys Chem Lett 2016 7 4891‐4897 7 Cerezo J Aranda D Avila F Mazzeo G Longhi G Abbate S Santoro F Chirality 2018 30 730ndash743 8 Cerezo J Liu Y Lin N Zhao X Improta R Santoro F J Chem Theory Comput 201814 820ndash832
I3
Defective but effective the role of defects on the electrocatalytic performance of oxide-based materials
for energy conversion
Ana B Muntildeoz Garciacutea1
1 Dipartimento di Fisica ldquoEttore Pancinirdquo Universitagrave di Napoli Federico II
Comp Univ Monte S Angelo via Cintia 21 80126 Napoli (Italia)
anabelenmunozgarciauninait
ABSTRACT
Ab initio simulations play an increasingly important role in materials sciences In the energy conversion scenario computational modeling can elucidate with atomic resolution the subtle composition-structure-property relationships behind the performance of functional materials and complex interfaces In heterogeneous electrocatalysis the underlying bulk and surface chargemass transport events are often strongly dependent on the presenceabsence of structural defects Thus a deep knowledge of defect chemistry is key for understanding tuning and optimizing the properties of different catalysts In particular this contribution will report recent advances in the DFT-based characterization of the role of defects in strongly correlated oxides as electrodes in electrocatalytic devices Three case studies will be presented (i) a new triple-conducting oxide based on Sr2Fe15Mo05O6 perovskite with promising bifunctional catalytic activity towards oxygen reduction and evolution reactions [1-3] (ii) Fe-doped ZrO2 for low temperature PEMFCs [4] and (iii) CuFeO2 delafossite for CO2 photoreduction [5] In all these cases we will discuss how surface oxygen vacancies -boosted by aliovalent doping- can improve the electrode performance and change product selectivity In conclusion this contribution will highlight the merits of computationally driven materials discovery in the context of energy conversion devices pointing out the importance of the necessary interplay between theory and experiment
REFERENCES
1 ABMG D Bugaris M Pavone J P Hodges A Huq F Chen H-C zur Loye E A Carter J Am Chem Soc 134 6826 (2012) 2 ABMG M Pavone Chem Mater 28 490 (2016) 3 ABMG M Pavone J Mater Chem A 5 12735 (2017) 4 P Madkikar D Menga G Harzer T Mittermeier A Siebel F E Wagner M Merz S Schuppler P Nagel ABMG M Pavone H A Gasteiger M Piana Submitted 5 J Gu A Wuttig J W Krizan Y Hu Z M Detweller R J Cava A B Bocarsly J Phys Chem C 117 12415 (2013)
I4
Solvent dynamics and energy transfer a real time description
Anna Painelli Francesco Di Maiolo
Dipartimento SCVSA Universitagrave di Parma annapainelliuniprit
ABSTRACT
Energy dissipation and relaxation phenomena are crucial to describe the dynamics of excited states The interaction of a molecule with the environment (the bath) is pivotal in this respect bringing theoretical chemistry towards the field of open quantum systems Several strategies are available to quantitatively describe the system-bath interaction most often based on the dynamics of the reduced density matrix Vibrational degrees of freedom must be explicitly described to address internal conversion and the huge dimension of the resulting basis imposes dramatic approximations to the calculation Here we face the problem adopting an essential state model (ESM) description of the molecular systems ESMs proved successful in describing low-energy linear and non-linear optical spectra of several families of organic dyes in terms of a minimal number of electronic states coupled to few effective vibrational modes ESMs successfully account for polar solvation and for intermolecular interactions in molecular aggregates and in energy transfer systems (1 2 3)
Here we present a dynamical non-adiabatic model for Resonance Energy Transfer (RET) Specifically we consider two dyes an energy donor (D) and an energy acceptor (A) Each dye corresponds to a push-pull chromophore described in terms of two electronic states coupled to a single effective vibration Accounting for dissipation phenomena within the Redfield approach we follow the real time dynamics of RET from the excited D towards A (Fig1 left panel) Moreover a newly derived multistate Redfield-Smoluchowski equation is used to investigate how the dynamical disorder induced by polar solvation affects RET (Fig1 right panel)
REFERENCES
1 F Terenziani A Painelli PhysChemChemPhys 17 13074-81 (2015) 2 C Sissa et al Phys Chem Chem Phys 2011 13 12734ndash12744 3 S Sanyal et al PhysChemChemPhys 2017 19 24979
Fig 1 Resonance
Energy Transfer in real
time Left Non-
adiabatic QUOTE
dynamics
following impulsive
excitation of the energy
donor the adiabatic
potential energy
surfaces are shown for
reference Right
temporal evolution of
the population of the
excited energy acceptor
in a frozen and liquid
polar solvent
I5
Towards an accurate computational photochemistry and photobiology the paradigmatic case of vision
Marco Garavelli1
1 Dipartimento di Chimica Industriale ldquoToso Montanarirdquo Viale del Risorgimento 4 40136 Bologna Italy 2 Affiliazione 2
marcogaravelliuniboit
ABSTRACT
The use of the computer to simulate light induced events in photoactive molecular materials has given access to a detailed description of the molecular motions and mechanisms underlying the reactivity of organic and bio-organic chromophores Thus different computational strategies and tools can now be operated like a ―virtual spectrometer to characterize and understand the photoinduced molecular deformation and reactivity of a given dye allowing for an accurate description of photochemicalphotobiological processes and a rational of the corresponding photophysical properties including time-resolved spectroscopy
This contribution reviews recent advances in this field by presenting methodological developments and applications in modeling the photophysicalphotochemical properties of organic chromophores and complex photoactive molecular architectures Retinal systems and visual proteins will be presented as a paradigmatic case [12] Hybrid QMMM calculations will be shown to be an elective tool for modeling photoinduced events and dynamics including tuningcontrolling effects of the environment For this purpose our new implementation of a general hybrid QMMM approach that is able to integrate some specialized softwares and acts as a flexible computational environment eventually allowing for so far inaccessible calculations (eg non-adiabatic molecular dynamics of unprecedented accuracy on large molecular materials) will be illustrated The information collected by these studies can be exploited for the design of novel photoactive molecular and soft materials including a novel paradigm of electrochromism for applications in a new generation of color tunable displays and e-ink devices Finally our latest achievements in developing (and modeling) non-linear bi-dimensional electronic spectroscopy as a novel diagnostic tool for tracking structuraldynamical problems in complex environments (eg biologically relevant systems such as proteins and DNA) will be presented [34]
REFERENCES
1 D Polli et al Nature 467 (2010) 440 2 B Demoulin et al JPCL 8 (2017) 4407 3 I Rivalta et al PCCP 16 (2014) 16865 4 I Rivalta et al JPCB 118 (2014) 8396
I6
Modellizzazione in fase condensata ad alte pressioni
Gianni Cardini
Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave di Firenze email giannicardiniunifiit
ABSTRACT
La modellizzazione delle proprietagrave strutturali e dinamiche di sistemi in fase condensata dipende essenzialmente dalla corretta descrizione del potenziale di interazione intermolecolare In simulazioni di dinamica molecolare1 si ricorre di solito a modelli di potenziale semi empirici o a metodi ab initio12 nella maggior parte dei casi basati sulla teoria del funzionale della densitagrave (DFT) Nel caso di sistemi sottoposti ad alte pressioni diventa cruciale una corretta descrizione delle interazioni a corto raggio e modelli che consentano eventualmente la rottura e formazione di legami chimici Verranno presentati alcuni risultati di simulazioni di dinamica molecolare ab initio con il metodo Car Parrinello Le simulazioni ab initio su fasi condensate basate su sistemi periodici sono dispendiose e pertanto condotte per tempi brevi e su campioni molto piccoli Inoltre nel campo delle alte pressioni gli sperimentali sono soliti interpretare i dati spettroscopici in termini di proprietagrave di singola molecola e necessitano di una modellizzazione possibilmente veloce per interpretare le loro misure Questo puograve essere ottenuto ricorrendo al metodo XP-PCM proposto da Cammi et al3 che consente di ottenere risultati qualitativi effettuando calcoli in condizioni estreme di pressione su singola molecola
REFERENCES
7 MP Allen amp DJ Tildesley Computer Simulation of Liquids Oxford University Press Oxford UK 2017 8 DMarx and J Hutter Ab Initio Molecular Dynamics Cambridge University Press Cambridge UK 2009 9 R Cammi et al Chem Phys 344 (2008) 135 R Cammi et al J ChemPhys 137 (2012) 154112
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
Diego Cesario
- Department of Chemistry and
Pharmaceutical Sciences and
Amsterdam Center for Multiscale
Modeling Vrije Universiteit
Amsterdam De Boelelaan 1083
1081 HV Amsterdam The
Netherlands
- Department of Chemistry
Biology and Biotechnology
University of Perugia
via Elce di Sotto 8 I-06123
Perugia Italy
Source of Cooperativity in Hydrogen-Bonded
Supramolecular Polymers
O9
Gloria Mazzone Chimie ParisTech PSL Research
University CNRS Institut de
Recherche de Chimie Paris Paris
France
Aiming at Color Prediction of Flexible Dyes in Aqueous
Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
O10
Michele Guerrini
Dipartimento FIM Universitagrave di
Modena e Reggio Emilia Italy
Solid-state effects on the optical excitation of push-pull
molecular J-aggregates by first principles simulations
O11
Mirco Zerbetto
Dipartimento di Scienze
Chimiche Universitagrave degli Studi
di Padova Padova 35313 Italia
Previsione dei Tempi di Rilassamento NMR di Molecole
Flessibili Oligosaccaridi come Caso di Studio
O12
F Faglioni
DSCG Univ of Modena and
Reggio Emilia Modena Italy
Self interaction charge delocalization electrolyte
ionization
O13
Mattia Anzola
Dipartimento di Scienze
Chimiche della Vita e della
Sostenibilitagrave Ambientale
Universitagrave degli Studi di Parma
Italy
Optical spectra of molecular aggregates testing
approximation schemes
O14
Martina De Vetta
-Institute of Theoretical
Chemistry Faculty of Chemistry
University of Vienna Waumlhringer
Str 17 A-1090 Vienna Austria
-Departamento de u mica
Universidad Aut noma de Madrid
Francisco Tomaacutes y Valiente 7
28049 Cantoblanco Madrid Spain
Simulations of a liposomal assisted delivery of the
Temoporfin photosensitizer
O15
Matteo Masetti Department of Pharmacy and
Biotechnology (FaBiT) Alma
Mater Studiorum ndash University of
Bologna Italy
The best of both worlds combining Markov State Models
and Path Collective Variables to describe protein-ligand
binding
O16
Ida Ritacco
CNR-IOM co SISSA via
Bonomea 265 34136 Trieste Italy
The mechanism of post-translation regulation of estrogen
biosynthesis in Breast cancer cells as revealed by atomic
level multiscale simulations
O17
Tommaso
Giovannini
Scuola Normale Superiore Piazza
dei Cavalieri 7 Pisa IT
Development of Theoretical Approaches to Model the
Spectral Properties of Complex Systems
O18
Fortuna Ponte
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria
Computational investigation of the platinum(IV)
anticancer prodrugs reduction mechanism by L-ascorbic
acid
O19
Laura Falivene
KAUST Catalysis Center King
Abdullah University of Science
and Technology Thuwal 23955-
6900 Saudi Arabia
Tuning Proximal and Remote Steric Effects in the
Rationalization of Catalytic Behavior
O20
E Schiavo
Department of Chemical Sciences
University of Naples Federico II
Comp Univ Monte SantrsquoAngelo
Via Cintia 21 80126 Naples Italy
Investigating photoelectrochemical properties of dye-
electrode interfaces with density functional embedding
theory
O21
Tainah Dorina
Marforio
Dipartimento di Chimica ldquoG
Ciamicianrdquo Alma Mater
Studiorum ndash Universitagrave di
Bologna via Selmi 2 40126
Bologna
Italy
CARBON NANOTUBES (CNTS) AS NANO-
REACTORS
REGIOSELECTIVITY AND KINETICS CONTROL
FOR
THE BROMINATION OF N-PHENYLACETAMIDE
A QMMM INVESTIGATION
O22
Poster Nome DipartimentoIstituzione Titolo contributo n
F Cappelluti
Universitagrave degli Studi dellrsquoAquila
- LrsquoAquila
F-RESP a fast and accurate polarizable force field P1
Francesco Tavanti
Department of Chemical and
Geological Sciences University of
Modena and Reggio Emilia Via
Campi 103 41125
Modena Italy
Natural compounds for Alzheimerrsquos disease treatment a
classical
Molecular Dynamics investigation
P2
E Bernes
Department of Chemical and
Pharmaceutical Sciences
University of Trieste 34127
Trieste Italy
Core-Electron Excitations in Dibenzothiophene
Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
P3
Baiano C
Department of Chemical Sciences
University of Naples Federico II
Ab initio characterization of CO2 photoreduction
mechanism at CuFeO2 delafossite electrode
P4
Davide Accomasso
Department of Chemistry and
Industrial Chemistry University
of Pisa Italy
Seeking new materials for singlet fission
covalent dimers as an alternative to molecular crystals
P5
Henry Adenusi
Chemistry Department University
of Rome ldquoLa Sapienzardquo Italy
Proton transfer mechanisms in protic ionic liquids P6
Giorgia Beata
Dipartimento di Chimica
Universitagrave di Torino Via Giuria 7
I-10125 Torino Italy
CRYSPLOT a new tool to visualize physical and
chemical properties of crystalline solids
P7
Marco Pagliai
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave degli Studi di
Firenze via della Lastruccia 3
50019 Sesto Fiorentino (FI) Italy
Molecular dynamics simulations of zinc proteins a
new force field
P8
Eslam M Moustafa
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria I-87036 Aracavacta
di Rende (CS) Italy
Reduction of Pt(IV) anticancer drugs a DFT mechanistic
study
P9
Alessandro Landi
Dipartimento di Chimica e
Biologia Adolfo Zambelli
Universitagrave di Salerno Via
Giovanni Paolo II I-84084
Fisciano (SA) Italy
Rapid evaluation of dynamic disorder in organic
semiconductors
P10
Isabella Romeo
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende I-87036
Italy
De novo proteins Insights from the theoretical
investigations
P11
Marina
Macchiagodena
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave degli Studi di
Firenze Via della Lastruccia 3 I-
50019 Sesto Fiorentino Italy
Improved force fields for molecular dynamics
simulations of zinc proteins
P12
Marco Fusegrave
Scuola Normale Superiore Piazza
dei Cavalieri 7 56126 Pisa Italy
Computational simulation of vibrationally resolved
spectra for spin‐forbidden transitionsforbidden transitions
P13
Tiziana Marino
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende I-87036
Italy
De novo proteins Insights from the theoretical
investigations
P14
Matteo Capone
Universitagrave dellrsquoAquila Italia Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
P15
J FREGONI
Dipartimento di scienze Fisiche
Informatiche e Matematiche
University of Modena and Reggio
Emilia I-41125 Modena Italy
Manipulating azobenzene photoisomerization
through strong light-molecule coupling
P16
Irene Conti
Dipartimento di Chimica
Industriale ldquo Toso Montanarirdquo
Universita di Bologna Viale del
Risorgimento 4 I-40136 Bologna
Italy
Excitonic State evolution of DNA Stacked Thymines
Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
P17
Andrea Le Donne
Chemistry department University
of Rome ldquoLa Sapienzardquo Rome
Italy
Ionic Liquids and Proton Transfer A Computational
Study to Understand Dynamic Processes
P18
Franco Egidi
Scuola Normale Superiore 56126
Pisa Italy
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
P19
Arianna Massaro
Department of Chemical Science
University of Naples ldquoFederico
IIrdquo via Cintia 21 80126 Naples
Italy
Unveiling the role of structural features in Na insertion
mechanism at anatase surfaces new insights for Na-ion
batteries development
P20
Alessandro Landi
Dipartimento di Chimica e
Biologia Adolfo Zambelli
Universitagrave di Salerno Via
Giovanni Paolo II I-84084
Fisciano (SA) Italy
Hole Mobility in Organic Semiconductors A Second-
Order Cumulant Approach
P21
Mariagrazia Fortino
Universitagrave di Modena e Reggio
Emilia Modena 41125 Italy
On the Simulation of Vibrationally Resolved Electronic
Spectra of medium-size molecules the case of Styryl
Substituted BODIPYs
P22
Marco Medves Dipdi Scienze Chimiche e
Farmaceutiche Universitagrave di
Trieste
Theoretical Study on the Circular Dichroism of Chiral
Bimetallic Clusters Ag-Au
P23
Jonathan Campeggio
Universitagrave degli Studi di Padova DiTe2 Calcolo del tensore di diffusione per molecole
flessibili
P24
Edoardo Jun
Mattioli
Chemistry Department ldquoG
Ciamicianrdquo University of Bologna
Computational Investigation of Competitive
Reaction Mechanisms inside Carbon Nanotubes
P25
Sergio Rampino
SMART Laboratory Scuola
Normale Superiore Piazza dei
Cavalieri 7 56126 Pisa
Combined Orbital-spaceReal-space Analysis of
Chemical Bonding through Virtual Reality
P26
Josephine Alba Dipdi Chimica Universitagrave di
Roma La Sapienza
Efficient and Accurate Modelling of Conformational
Transitions in proteins comparison between two Src
kinase proteins
P27
Abstracts delle conferenze su invito
I1
Solving the Schroumldinger equation in a box wavepackets and continuum states
Piero Decleva
DSCF Universitarsquo di Trieste declevaunitsit
ABSTRACT
Nelle molecole gli stati elettronici piursquo bassi decadono esponenzialmente con unrsquoestensione spaziale molto limitata Questo non ersquo piursquo vero per
- Stati Rydberg con alti numeri quantici - Stati del continuo - Pacchetti generati da impulsi elettromagnetici molto intensi
In tal caso le basi LCAO costruite da GTO o STO risultano inadeguate e sono necessari approcci alternativi sia funzioni di base diverse sia uso di griglie numeriche Per lo studio del continuo elettronico abbiamo da tempo sviluppato un set basato sullrsquouso di B-spline [1] come funzioni radiali adoperate nel modo LCAO convenzionale che si ersquo dimostrato assai flessibile e accurato Queste forniscono unrsquoeccellente rappresentazione delle soluzioni dellrsquoequazione di Schroumldinger allrsquointerno di una sfera di raggio prefissato arbitrario Calcoli dei parametri di fotoionizzazione molecolare a livello DFT [2] o TDDFT [3] forniscono generalmente risultati in buon accordo con lrsquoesperimento anche per sistemi relativamente grandi e per un gran numero di osservabili di fotoionizzazione sezioni drsquourto distribuzioni angolari di molecole con orientazione fissa o casuale parametri non-dipolari effetti di interferenza e diffrazione parametri chirali Ersquo stata anche applicata a fotoionizzazione risolta nel tempo da stati eccitati in esperimenti pump-probe e alla generazione di pacchetti di cationi da impulsi ultraveloci Piursquo recentemente la base ersquo stata applicata al calcolo di pacchetti drsquoonda eccitati da impulsi laser in regime non perturbativo Durante lrsquoimpulso lrsquoescursione dellrsquoelettrone puorsquo raggiungere migliaia di unitarsquo atomiche ma lrsquoapproccio ersquo numericamente molto stabile e si presta bene all propagazione del pacchetto per risoluzione dellrsquoequazione temporale Ersquo stata considerata la ionizzazione totale in funzione dellrsquoorientazione del campo rispetto alla molecola [4] il calcolo dello spettro di elettroni risolto in energia ed angolo attraverso la proiezione sugli autostati del continuo la rivelazione di pacchetti elettronici coerenti in esperimenti pump-probe agli attosecondi [5] la generazione di armoniche alte (HHG) [6] Verranno illustrati alcuni risultati recenti e discusse le linee di sviluppo
REFERENCES
1 H Bachau E Cormier P Decleva J E Hansen and F Martin ldquoApplications of B-splines in Atomic and Molecular Physicsrdquo
Reports on Progress in Physics 64 1815 (2001)
2 D Toffoli M Stener G Fronzoni and P Decleva ldquoConvergenge of the Multicenter B-spline DFT approach for the continuumrdquo
Chem Phys 276 25 (2002)
3 M Stener G Fronzoni and P Decleva ldquoTime-dependent density-functional theory for molecular photoionization with
noniterative algorithm and multicenter B-spline basis set CS2 and C6H6 case studiesrdquoJ Chem Phys 122 (2005) 234301
4 S Petretti YV Vanne A Saenz A Castro and P Decleva ldquoAlignment-Dependent Ionization of N2 O2 and CO2 in Intense
Laser Fieldsrdquo Phys Rev Letters 104 (2010) 223001
5 M Ruberti P Decleva and V Averbukh ldquoMulti-channel dynamics and correlation-driven inter-channel couplings in high
harmonic generation spectra of aligned CO2 molecule ab initio Time Dependent B-spline ADC ab initio analysisrdquo Phys Chem
Chem Phys 20 (2018) 8311
6 E Plesiat M Lara-Astiaso P Decleva A Palacios and F Martin ldquoReal-time determination of ultrafast charge dynamics in
tetrafluoromethane from attosecond pump-probe photoelectron spectroscopyrdquo Chem Eur J 242018 xxx
I2
Mixed quantumclassical description of the effects of nuclear motion in electronic spectroscopy and ultrafast
photophysics
Fabrizio Santoro1
1 ICCOM-CNR Area della Ricerca del CNR di Pisa Italy 2 Affiliazione 2
fabriziosantoroiccomcnrit
ABSTRACT
Quantum nuclear effects can play a relevant role in determining the shape of electronic spectra and the fate of the photoexcited dynamics in molecular systems Recent advancements in fully quantum vibronic approaches for the computation of spectra [12] and in quantum-dynamical (QD) approaches like those provided by the MCTDH method [3-5] allow an efficient description of such effects even in large systems if they are rigid (harmonic) and in gas phase Flexible systems or systems embedded in solvents or in heterogenoeus media possibly establishing with them specific interactions represent a challenge for fully quantum treatments of nuclear motions Classical and semi-classical trajectory based approaches are very well suited to deal with these cases but they neglect quantum nuclear effects We believe that the development of wise mixed quantum classical (MQC) approaches may represent a suitable framework to overcome some of these present limitations In this contribution we present our recent work in this field In electronic spectroscopy we introduced mixed schemes that separate fast and slow degrees of freedom (DoF) on the grounds of an adiabatic approximation and treat the fast DoF at quantum level and the slow ones (including the solvent) at classical level The spectra are then naturally expressed as an average of vibronic spectra involving along the fast DoF over the distribution of the classical DoF [5-7] Extending these ideas to ultrafast photophysical processes we recently proposed a MQC approach to introduce environmental dynamical effects in QD simulations In its simplest version all the solute degrees of freedom are represented by a wavepacket moving according to nonadiabatic quantum dynamics while the motion of an explicit solvent model is described by an ensemble of classical trajectories The core idea of the method is to describe the mutual coupling of the solute and solvent dynamics within a mean-field framework In this way the Hamiltonians of both the quantum and classical subsystems contain time-dependent terms due to the interaction with the other subset and the quantum and classical equations of motions are solved simultaneously We will discuss the potentialities limitations and possible perspectives of these methods with a number of test applications
REFERENCES
1 Barone V WIREs Comput Mol Sci 2016 6 86-110 2 Santoro F Jacquemin D WIREs Comput Mol Sci 2016 6 460-486 3 Wang H Thoss M J Chem Phys 2003 119 1289minus1299 Vendrell O Meyer H-D J Chem Phys 2011 134 044135 4 Beck M H J ckle A Worth G A Meyer H-D Phys Rep 2000 324 1minus105 5 CerezoJ Avila F Prampolini G Santoro F J Chem Theory Comput 2015 11 5810ndash5825
6 Cerezo J Mazzeo G Longhi G Abbate S Santoro F J Phys Chem Lett 2016 7 4891‐4897 7 Cerezo J Aranda D Avila F Mazzeo G Longhi G Abbate S Santoro F Chirality 2018 30 730ndash743 8 Cerezo J Liu Y Lin N Zhao X Improta R Santoro F J Chem Theory Comput 201814 820ndash832
I3
Defective but effective the role of defects on the electrocatalytic performance of oxide-based materials
for energy conversion
Ana B Muntildeoz Garciacutea1
1 Dipartimento di Fisica ldquoEttore Pancinirdquo Universitagrave di Napoli Federico II
Comp Univ Monte S Angelo via Cintia 21 80126 Napoli (Italia)
anabelenmunozgarciauninait
ABSTRACT
Ab initio simulations play an increasingly important role in materials sciences In the energy conversion scenario computational modeling can elucidate with atomic resolution the subtle composition-structure-property relationships behind the performance of functional materials and complex interfaces In heterogeneous electrocatalysis the underlying bulk and surface chargemass transport events are often strongly dependent on the presenceabsence of structural defects Thus a deep knowledge of defect chemistry is key for understanding tuning and optimizing the properties of different catalysts In particular this contribution will report recent advances in the DFT-based characterization of the role of defects in strongly correlated oxides as electrodes in electrocatalytic devices Three case studies will be presented (i) a new triple-conducting oxide based on Sr2Fe15Mo05O6 perovskite with promising bifunctional catalytic activity towards oxygen reduction and evolution reactions [1-3] (ii) Fe-doped ZrO2 for low temperature PEMFCs [4] and (iii) CuFeO2 delafossite for CO2 photoreduction [5] In all these cases we will discuss how surface oxygen vacancies -boosted by aliovalent doping- can improve the electrode performance and change product selectivity In conclusion this contribution will highlight the merits of computationally driven materials discovery in the context of energy conversion devices pointing out the importance of the necessary interplay between theory and experiment
REFERENCES
1 ABMG D Bugaris M Pavone J P Hodges A Huq F Chen H-C zur Loye E A Carter J Am Chem Soc 134 6826 (2012) 2 ABMG M Pavone Chem Mater 28 490 (2016) 3 ABMG M Pavone J Mater Chem A 5 12735 (2017) 4 P Madkikar D Menga G Harzer T Mittermeier A Siebel F E Wagner M Merz S Schuppler P Nagel ABMG M Pavone H A Gasteiger M Piana Submitted 5 J Gu A Wuttig J W Krizan Y Hu Z M Detweller R J Cava A B Bocarsly J Phys Chem C 117 12415 (2013)
I4
Solvent dynamics and energy transfer a real time description
Anna Painelli Francesco Di Maiolo
Dipartimento SCVSA Universitagrave di Parma annapainelliuniprit
ABSTRACT
Energy dissipation and relaxation phenomena are crucial to describe the dynamics of excited states The interaction of a molecule with the environment (the bath) is pivotal in this respect bringing theoretical chemistry towards the field of open quantum systems Several strategies are available to quantitatively describe the system-bath interaction most often based on the dynamics of the reduced density matrix Vibrational degrees of freedom must be explicitly described to address internal conversion and the huge dimension of the resulting basis imposes dramatic approximations to the calculation Here we face the problem adopting an essential state model (ESM) description of the molecular systems ESMs proved successful in describing low-energy linear and non-linear optical spectra of several families of organic dyes in terms of a minimal number of electronic states coupled to few effective vibrational modes ESMs successfully account for polar solvation and for intermolecular interactions in molecular aggregates and in energy transfer systems (1 2 3)
Here we present a dynamical non-adiabatic model for Resonance Energy Transfer (RET) Specifically we consider two dyes an energy donor (D) and an energy acceptor (A) Each dye corresponds to a push-pull chromophore described in terms of two electronic states coupled to a single effective vibration Accounting for dissipation phenomena within the Redfield approach we follow the real time dynamics of RET from the excited D towards A (Fig1 left panel) Moreover a newly derived multistate Redfield-Smoluchowski equation is used to investigate how the dynamical disorder induced by polar solvation affects RET (Fig1 right panel)
REFERENCES
1 F Terenziani A Painelli PhysChemChemPhys 17 13074-81 (2015) 2 C Sissa et al Phys Chem Chem Phys 2011 13 12734ndash12744 3 S Sanyal et al PhysChemChemPhys 2017 19 24979
Fig 1 Resonance
Energy Transfer in real
time Left Non-
adiabatic QUOTE
dynamics
following impulsive
excitation of the energy
donor the adiabatic
potential energy
surfaces are shown for
reference Right
temporal evolution of
the population of the
excited energy acceptor
in a frozen and liquid
polar solvent
I5
Towards an accurate computational photochemistry and photobiology the paradigmatic case of vision
Marco Garavelli1
1 Dipartimento di Chimica Industriale ldquoToso Montanarirdquo Viale del Risorgimento 4 40136 Bologna Italy 2 Affiliazione 2
marcogaravelliuniboit
ABSTRACT
The use of the computer to simulate light induced events in photoactive molecular materials has given access to a detailed description of the molecular motions and mechanisms underlying the reactivity of organic and bio-organic chromophores Thus different computational strategies and tools can now be operated like a ―virtual spectrometer to characterize and understand the photoinduced molecular deformation and reactivity of a given dye allowing for an accurate description of photochemicalphotobiological processes and a rational of the corresponding photophysical properties including time-resolved spectroscopy
This contribution reviews recent advances in this field by presenting methodological developments and applications in modeling the photophysicalphotochemical properties of organic chromophores and complex photoactive molecular architectures Retinal systems and visual proteins will be presented as a paradigmatic case [12] Hybrid QMMM calculations will be shown to be an elective tool for modeling photoinduced events and dynamics including tuningcontrolling effects of the environment For this purpose our new implementation of a general hybrid QMMM approach that is able to integrate some specialized softwares and acts as a flexible computational environment eventually allowing for so far inaccessible calculations (eg non-adiabatic molecular dynamics of unprecedented accuracy on large molecular materials) will be illustrated The information collected by these studies can be exploited for the design of novel photoactive molecular and soft materials including a novel paradigm of electrochromism for applications in a new generation of color tunable displays and e-ink devices Finally our latest achievements in developing (and modeling) non-linear bi-dimensional electronic spectroscopy as a novel diagnostic tool for tracking structuraldynamical problems in complex environments (eg biologically relevant systems such as proteins and DNA) will be presented [34]
REFERENCES
1 D Polli et al Nature 467 (2010) 440 2 B Demoulin et al JPCL 8 (2017) 4407 3 I Rivalta et al PCCP 16 (2014) 16865 4 I Rivalta et al JPCB 118 (2014) 8396
I6
Modellizzazione in fase condensata ad alte pressioni
Gianni Cardini
Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave di Firenze email giannicardiniunifiit
ABSTRACT
La modellizzazione delle proprietagrave strutturali e dinamiche di sistemi in fase condensata dipende essenzialmente dalla corretta descrizione del potenziale di interazione intermolecolare In simulazioni di dinamica molecolare1 si ricorre di solito a modelli di potenziale semi empirici o a metodi ab initio12 nella maggior parte dei casi basati sulla teoria del funzionale della densitagrave (DFT) Nel caso di sistemi sottoposti ad alte pressioni diventa cruciale una corretta descrizione delle interazioni a corto raggio e modelli che consentano eventualmente la rottura e formazione di legami chimici Verranno presentati alcuni risultati di simulazioni di dinamica molecolare ab initio con il metodo Car Parrinello Le simulazioni ab initio su fasi condensate basate su sistemi periodici sono dispendiose e pertanto condotte per tempi brevi e su campioni molto piccoli Inoltre nel campo delle alte pressioni gli sperimentali sono soliti interpretare i dati spettroscopici in termini di proprietagrave di singola molecola e necessitano di una modellizzazione possibilmente veloce per interpretare le loro misure Questo puograve essere ottenuto ricorrendo al metodo XP-PCM proposto da Cammi et al3 che consente di ottenere risultati qualitativi effettuando calcoli in condizioni estreme di pressione su singola molecola
REFERENCES
7 MP Allen amp DJ Tildesley Computer Simulation of Liquids Oxford University Press Oxford UK 2017 8 DMarx and J Hutter Ab Initio Molecular Dynamics Cambridge University Press Cambridge UK 2009 9 R Cammi et al Chem Phys 344 (2008) 135 R Cammi et al J ChemPhys 137 (2012) 154112
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
Poster Nome DipartimentoIstituzione Titolo contributo n
F Cappelluti
Universitagrave degli Studi dellrsquoAquila
- LrsquoAquila
F-RESP a fast and accurate polarizable force field P1
Francesco Tavanti
Department of Chemical and
Geological Sciences University of
Modena and Reggio Emilia Via
Campi 103 41125
Modena Italy
Natural compounds for Alzheimerrsquos disease treatment a
classical
Molecular Dynamics investigation
P2
E Bernes
Department of Chemical and
Pharmaceutical Sciences
University of Trieste 34127
Trieste Italy
Core-Electron Excitations in Dibenzothiophene
Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
P3
Baiano C
Department of Chemical Sciences
University of Naples Federico II
Ab initio characterization of CO2 photoreduction
mechanism at CuFeO2 delafossite electrode
P4
Davide Accomasso
Department of Chemistry and
Industrial Chemistry University
of Pisa Italy
Seeking new materials for singlet fission
covalent dimers as an alternative to molecular crystals
P5
Henry Adenusi
Chemistry Department University
of Rome ldquoLa Sapienzardquo Italy
Proton transfer mechanisms in protic ionic liquids P6
Giorgia Beata
Dipartimento di Chimica
Universitagrave di Torino Via Giuria 7
I-10125 Torino Italy
CRYSPLOT a new tool to visualize physical and
chemical properties of crystalline solids
P7
Marco Pagliai
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave degli Studi di
Firenze via della Lastruccia 3
50019 Sesto Fiorentino (FI) Italy
Molecular dynamics simulations of zinc proteins a
new force field
P8
Eslam M Moustafa
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria I-87036 Aracavacta
di Rende (CS) Italy
Reduction of Pt(IV) anticancer drugs a DFT mechanistic
study
P9
Alessandro Landi
Dipartimento di Chimica e
Biologia Adolfo Zambelli
Universitagrave di Salerno Via
Giovanni Paolo II I-84084
Fisciano (SA) Italy
Rapid evaluation of dynamic disorder in organic
semiconductors
P10
Isabella Romeo
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende I-87036
Italy
De novo proteins Insights from the theoretical
investigations
P11
Marina
Macchiagodena
Dipartimento di Chimica ldquoUgo
Schiffrdquo Universitagrave degli Studi di
Firenze Via della Lastruccia 3 I-
50019 Sesto Fiorentino Italy
Improved force fields for molecular dynamics
simulations of zinc proteins
P12
Marco Fusegrave
Scuola Normale Superiore Piazza
dei Cavalieri 7 56126 Pisa Italy
Computational simulation of vibrationally resolved
spectra for spin‐forbidden transitionsforbidden transitions
P13
Tiziana Marino
Dipartimento di Chimica e
Tecnologie Chimiche Universitagrave
della Calabria Rende I-87036
Italy
De novo proteins Insights from the theoretical
investigations
P14
Matteo Capone
Universitagrave dellrsquoAquila Italia Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
P15
J FREGONI
Dipartimento di scienze Fisiche
Informatiche e Matematiche
University of Modena and Reggio
Emilia I-41125 Modena Italy
Manipulating azobenzene photoisomerization
through strong light-molecule coupling
P16
Irene Conti
Dipartimento di Chimica
Industriale ldquo Toso Montanarirdquo
Universita di Bologna Viale del
Risorgimento 4 I-40136 Bologna
Italy
Excitonic State evolution of DNA Stacked Thymines
Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
P17
Andrea Le Donne
Chemistry department University
of Rome ldquoLa Sapienzardquo Rome
Italy
Ionic Liquids and Proton Transfer A Computational
Study to Understand Dynamic Processes
P18
Franco Egidi
Scuola Normale Superiore 56126
Pisa Italy
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
P19
Arianna Massaro
Department of Chemical Science
University of Naples ldquoFederico
IIrdquo via Cintia 21 80126 Naples
Italy
Unveiling the role of structural features in Na insertion
mechanism at anatase surfaces new insights for Na-ion
batteries development
P20
Alessandro Landi
Dipartimento di Chimica e
Biologia Adolfo Zambelli
Universitagrave di Salerno Via
Giovanni Paolo II I-84084
Fisciano (SA) Italy
Hole Mobility in Organic Semiconductors A Second-
Order Cumulant Approach
P21
Mariagrazia Fortino
Universitagrave di Modena e Reggio
Emilia Modena 41125 Italy
On the Simulation of Vibrationally Resolved Electronic
Spectra of medium-size molecules the case of Styryl
Substituted BODIPYs
P22
Marco Medves Dipdi Scienze Chimiche e
Farmaceutiche Universitagrave di
Trieste
Theoretical Study on the Circular Dichroism of Chiral
Bimetallic Clusters Ag-Au
P23
Jonathan Campeggio
Universitagrave degli Studi di Padova DiTe2 Calcolo del tensore di diffusione per molecole
flessibili
P24
Edoardo Jun
Mattioli
Chemistry Department ldquoG
Ciamicianrdquo University of Bologna
Computational Investigation of Competitive
Reaction Mechanisms inside Carbon Nanotubes
P25
Sergio Rampino
SMART Laboratory Scuola
Normale Superiore Piazza dei
Cavalieri 7 56126 Pisa
Combined Orbital-spaceReal-space Analysis of
Chemical Bonding through Virtual Reality
P26
Josephine Alba Dipdi Chimica Universitagrave di
Roma La Sapienza
Efficient and Accurate Modelling of Conformational
Transitions in proteins comparison between two Src
kinase proteins
P27
Abstracts delle conferenze su invito
I1
Solving the Schroumldinger equation in a box wavepackets and continuum states
Piero Decleva
DSCF Universitarsquo di Trieste declevaunitsit
ABSTRACT
Nelle molecole gli stati elettronici piursquo bassi decadono esponenzialmente con unrsquoestensione spaziale molto limitata Questo non ersquo piursquo vero per
- Stati Rydberg con alti numeri quantici - Stati del continuo - Pacchetti generati da impulsi elettromagnetici molto intensi
In tal caso le basi LCAO costruite da GTO o STO risultano inadeguate e sono necessari approcci alternativi sia funzioni di base diverse sia uso di griglie numeriche Per lo studio del continuo elettronico abbiamo da tempo sviluppato un set basato sullrsquouso di B-spline [1] come funzioni radiali adoperate nel modo LCAO convenzionale che si ersquo dimostrato assai flessibile e accurato Queste forniscono unrsquoeccellente rappresentazione delle soluzioni dellrsquoequazione di Schroumldinger allrsquointerno di una sfera di raggio prefissato arbitrario Calcoli dei parametri di fotoionizzazione molecolare a livello DFT [2] o TDDFT [3] forniscono generalmente risultati in buon accordo con lrsquoesperimento anche per sistemi relativamente grandi e per un gran numero di osservabili di fotoionizzazione sezioni drsquourto distribuzioni angolari di molecole con orientazione fissa o casuale parametri non-dipolari effetti di interferenza e diffrazione parametri chirali Ersquo stata anche applicata a fotoionizzazione risolta nel tempo da stati eccitati in esperimenti pump-probe e alla generazione di pacchetti di cationi da impulsi ultraveloci Piursquo recentemente la base ersquo stata applicata al calcolo di pacchetti drsquoonda eccitati da impulsi laser in regime non perturbativo Durante lrsquoimpulso lrsquoescursione dellrsquoelettrone puorsquo raggiungere migliaia di unitarsquo atomiche ma lrsquoapproccio ersquo numericamente molto stabile e si presta bene all propagazione del pacchetto per risoluzione dellrsquoequazione temporale Ersquo stata considerata la ionizzazione totale in funzione dellrsquoorientazione del campo rispetto alla molecola [4] il calcolo dello spettro di elettroni risolto in energia ed angolo attraverso la proiezione sugli autostati del continuo la rivelazione di pacchetti elettronici coerenti in esperimenti pump-probe agli attosecondi [5] la generazione di armoniche alte (HHG) [6] Verranno illustrati alcuni risultati recenti e discusse le linee di sviluppo
REFERENCES
1 H Bachau E Cormier P Decleva J E Hansen and F Martin ldquoApplications of B-splines in Atomic and Molecular Physicsrdquo
Reports on Progress in Physics 64 1815 (2001)
2 D Toffoli M Stener G Fronzoni and P Decleva ldquoConvergenge of the Multicenter B-spline DFT approach for the continuumrdquo
Chem Phys 276 25 (2002)
3 M Stener G Fronzoni and P Decleva ldquoTime-dependent density-functional theory for molecular photoionization with
noniterative algorithm and multicenter B-spline basis set CS2 and C6H6 case studiesrdquoJ Chem Phys 122 (2005) 234301
4 S Petretti YV Vanne A Saenz A Castro and P Decleva ldquoAlignment-Dependent Ionization of N2 O2 and CO2 in Intense
Laser Fieldsrdquo Phys Rev Letters 104 (2010) 223001
5 M Ruberti P Decleva and V Averbukh ldquoMulti-channel dynamics and correlation-driven inter-channel couplings in high
harmonic generation spectra of aligned CO2 molecule ab initio Time Dependent B-spline ADC ab initio analysisrdquo Phys Chem
Chem Phys 20 (2018) 8311
6 E Plesiat M Lara-Astiaso P Decleva A Palacios and F Martin ldquoReal-time determination of ultrafast charge dynamics in
tetrafluoromethane from attosecond pump-probe photoelectron spectroscopyrdquo Chem Eur J 242018 xxx
I2
Mixed quantumclassical description of the effects of nuclear motion in electronic spectroscopy and ultrafast
photophysics
Fabrizio Santoro1
1 ICCOM-CNR Area della Ricerca del CNR di Pisa Italy 2 Affiliazione 2
fabriziosantoroiccomcnrit
ABSTRACT
Quantum nuclear effects can play a relevant role in determining the shape of electronic spectra and the fate of the photoexcited dynamics in molecular systems Recent advancements in fully quantum vibronic approaches for the computation of spectra [12] and in quantum-dynamical (QD) approaches like those provided by the MCTDH method [3-5] allow an efficient description of such effects even in large systems if they are rigid (harmonic) and in gas phase Flexible systems or systems embedded in solvents or in heterogenoeus media possibly establishing with them specific interactions represent a challenge for fully quantum treatments of nuclear motions Classical and semi-classical trajectory based approaches are very well suited to deal with these cases but they neglect quantum nuclear effects We believe that the development of wise mixed quantum classical (MQC) approaches may represent a suitable framework to overcome some of these present limitations In this contribution we present our recent work in this field In electronic spectroscopy we introduced mixed schemes that separate fast and slow degrees of freedom (DoF) on the grounds of an adiabatic approximation and treat the fast DoF at quantum level and the slow ones (including the solvent) at classical level The spectra are then naturally expressed as an average of vibronic spectra involving along the fast DoF over the distribution of the classical DoF [5-7] Extending these ideas to ultrafast photophysical processes we recently proposed a MQC approach to introduce environmental dynamical effects in QD simulations In its simplest version all the solute degrees of freedom are represented by a wavepacket moving according to nonadiabatic quantum dynamics while the motion of an explicit solvent model is described by an ensemble of classical trajectories The core idea of the method is to describe the mutual coupling of the solute and solvent dynamics within a mean-field framework In this way the Hamiltonians of both the quantum and classical subsystems contain time-dependent terms due to the interaction with the other subset and the quantum and classical equations of motions are solved simultaneously We will discuss the potentialities limitations and possible perspectives of these methods with a number of test applications
REFERENCES
1 Barone V WIREs Comput Mol Sci 2016 6 86-110 2 Santoro F Jacquemin D WIREs Comput Mol Sci 2016 6 460-486 3 Wang H Thoss M J Chem Phys 2003 119 1289minus1299 Vendrell O Meyer H-D J Chem Phys 2011 134 044135 4 Beck M H J ckle A Worth G A Meyer H-D Phys Rep 2000 324 1minus105 5 CerezoJ Avila F Prampolini G Santoro F J Chem Theory Comput 2015 11 5810ndash5825
6 Cerezo J Mazzeo G Longhi G Abbate S Santoro F J Phys Chem Lett 2016 7 4891‐4897 7 Cerezo J Aranda D Avila F Mazzeo G Longhi G Abbate S Santoro F Chirality 2018 30 730ndash743 8 Cerezo J Liu Y Lin N Zhao X Improta R Santoro F J Chem Theory Comput 201814 820ndash832
I3
Defective but effective the role of defects on the electrocatalytic performance of oxide-based materials
for energy conversion
Ana B Muntildeoz Garciacutea1
1 Dipartimento di Fisica ldquoEttore Pancinirdquo Universitagrave di Napoli Federico II
Comp Univ Monte S Angelo via Cintia 21 80126 Napoli (Italia)
anabelenmunozgarciauninait
ABSTRACT
Ab initio simulations play an increasingly important role in materials sciences In the energy conversion scenario computational modeling can elucidate with atomic resolution the subtle composition-structure-property relationships behind the performance of functional materials and complex interfaces In heterogeneous electrocatalysis the underlying bulk and surface chargemass transport events are often strongly dependent on the presenceabsence of structural defects Thus a deep knowledge of defect chemistry is key for understanding tuning and optimizing the properties of different catalysts In particular this contribution will report recent advances in the DFT-based characterization of the role of defects in strongly correlated oxides as electrodes in electrocatalytic devices Three case studies will be presented (i) a new triple-conducting oxide based on Sr2Fe15Mo05O6 perovskite with promising bifunctional catalytic activity towards oxygen reduction and evolution reactions [1-3] (ii) Fe-doped ZrO2 for low temperature PEMFCs [4] and (iii) CuFeO2 delafossite for CO2 photoreduction [5] In all these cases we will discuss how surface oxygen vacancies -boosted by aliovalent doping- can improve the electrode performance and change product selectivity In conclusion this contribution will highlight the merits of computationally driven materials discovery in the context of energy conversion devices pointing out the importance of the necessary interplay between theory and experiment
REFERENCES
1 ABMG D Bugaris M Pavone J P Hodges A Huq F Chen H-C zur Loye E A Carter J Am Chem Soc 134 6826 (2012) 2 ABMG M Pavone Chem Mater 28 490 (2016) 3 ABMG M Pavone J Mater Chem A 5 12735 (2017) 4 P Madkikar D Menga G Harzer T Mittermeier A Siebel F E Wagner M Merz S Schuppler P Nagel ABMG M Pavone H A Gasteiger M Piana Submitted 5 J Gu A Wuttig J W Krizan Y Hu Z M Detweller R J Cava A B Bocarsly J Phys Chem C 117 12415 (2013)
I4
Solvent dynamics and energy transfer a real time description
Anna Painelli Francesco Di Maiolo
Dipartimento SCVSA Universitagrave di Parma annapainelliuniprit
ABSTRACT
Energy dissipation and relaxation phenomena are crucial to describe the dynamics of excited states The interaction of a molecule with the environment (the bath) is pivotal in this respect bringing theoretical chemistry towards the field of open quantum systems Several strategies are available to quantitatively describe the system-bath interaction most often based on the dynamics of the reduced density matrix Vibrational degrees of freedom must be explicitly described to address internal conversion and the huge dimension of the resulting basis imposes dramatic approximations to the calculation Here we face the problem adopting an essential state model (ESM) description of the molecular systems ESMs proved successful in describing low-energy linear and non-linear optical spectra of several families of organic dyes in terms of a minimal number of electronic states coupled to few effective vibrational modes ESMs successfully account for polar solvation and for intermolecular interactions in molecular aggregates and in energy transfer systems (1 2 3)
Here we present a dynamical non-adiabatic model for Resonance Energy Transfer (RET) Specifically we consider two dyes an energy donor (D) and an energy acceptor (A) Each dye corresponds to a push-pull chromophore described in terms of two electronic states coupled to a single effective vibration Accounting for dissipation phenomena within the Redfield approach we follow the real time dynamics of RET from the excited D towards A (Fig1 left panel) Moreover a newly derived multistate Redfield-Smoluchowski equation is used to investigate how the dynamical disorder induced by polar solvation affects RET (Fig1 right panel)
REFERENCES
1 F Terenziani A Painelli PhysChemChemPhys 17 13074-81 (2015) 2 C Sissa et al Phys Chem Chem Phys 2011 13 12734ndash12744 3 S Sanyal et al PhysChemChemPhys 2017 19 24979
Fig 1 Resonance
Energy Transfer in real
time Left Non-
adiabatic QUOTE
dynamics
following impulsive
excitation of the energy
donor the adiabatic
potential energy
surfaces are shown for
reference Right
temporal evolution of
the population of the
excited energy acceptor
in a frozen and liquid
polar solvent
I5
Towards an accurate computational photochemistry and photobiology the paradigmatic case of vision
Marco Garavelli1
1 Dipartimento di Chimica Industriale ldquoToso Montanarirdquo Viale del Risorgimento 4 40136 Bologna Italy 2 Affiliazione 2
marcogaravelliuniboit
ABSTRACT
The use of the computer to simulate light induced events in photoactive molecular materials has given access to a detailed description of the molecular motions and mechanisms underlying the reactivity of organic and bio-organic chromophores Thus different computational strategies and tools can now be operated like a ―virtual spectrometer to characterize and understand the photoinduced molecular deformation and reactivity of a given dye allowing for an accurate description of photochemicalphotobiological processes and a rational of the corresponding photophysical properties including time-resolved spectroscopy
This contribution reviews recent advances in this field by presenting methodological developments and applications in modeling the photophysicalphotochemical properties of organic chromophores and complex photoactive molecular architectures Retinal systems and visual proteins will be presented as a paradigmatic case [12] Hybrid QMMM calculations will be shown to be an elective tool for modeling photoinduced events and dynamics including tuningcontrolling effects of the environment For this purpose our new implementation of a general hybrid QMMM approach that is able to integrate some specialized softwares and acts as a flexible computational environment eventually allowing for so far inaccessible calculations (eg non-adiabatic molecular dynamics of unprecedented accuracy on large molecular materials) will be illustrated The information collected by these studies can be exploited for the design of novel photoactive molecular and soft materials including a novel paradigm of electrochromism for applications in a new generation of color tunable displays and e-ink devices Finally our latest achievements in developing (and modeling) non-linear bi-dimensional electronic spectroscopy as a novel diagnostic tool for tracking structuraldynamical problems in complex environments (eg biologically relevant systems such as proteins and DNA) will be presented [34]
REFERENCES
1 D Polli et al Nature 467 (2010) 440 2 B Demoulin et al JPCL 8 (2017) 4407 3 I Rivalta et al PCCP 16 (2014) 16865 4 I Rivalta et al JPCB 118 (2014) 8396
I6
Modellizzazione in fase condensata ad alte pressioni
Gianni Cardini
Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave di Firenze email giannicardiniunifiit
ABSTRACT
La modellizzazione delle proprietagrave strutturali e dinamiche di sistemi in fase condensata dipende essenzialmente dalla corretta descrizione del potenziale di interazione intermolecolare In simulazioni di dinamica molecolare1 si ricorre di solito a modelli di potenziale semi empirici o a metodi ab initio12 nella maggior parte dei casi basati sulla teoria del funzionale della densitagrave (DFT) Nel caso di sistemi sottoposti ad alte pressioni diventa cruciale una corretta descrizione delle interazioni a corto raggio e modelli che consentano eventualmente la rottura e formazione di legami chimici Verranno presentati alcuni risultati di simulazioni di dinamica molecolare ab initio con il metodo Car Parrinello Le simulazioni ab initio su fasi condensate basate su sistemi periodici sono dispendiose e pertanto condotte per tempi brevi e su campioni molto piccoli Inoltre nel campo delle alte pressioni gli sperimentali sono soliti interpretare i dati spettroscopici in termini di proprietagrave di singola molecola e necessitano di una modellizzazione possibilmente veloce per interpretare le loro misure Questo puograve essere ottenuto ricorrendo al metodo XP-PCM proposto da Cammi et al3 che consente di ottenere risultati qualitativi effettuando calcoli in condizioni estreme di pressione su singola molecola
REFERENCES
7 MP Allen amp DJ Tildesley Computer Simulation of Liquids Oxford University Press Oxford UK 2017 8 DMarx and J Hutter Ab Initio Molecular Dynamics Cambridge University Press Cambridge UK 2009 9 R Cammi et al Chem Phys 344 (2008) 135 R Cammi et al J ChemPhys 137 (2012) 154112
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
Franco Egidi
Scuola Normale Superiore 56126
Pisa Italy
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
P19
Arianna Massaro
Department of Chemical Science
University of Naples ldquoFederico
IIrdquo via Cintia 21 80126 Naples
Italy
Unveiling the role of structural features in Na insertion
mechanism at anatase surfaces new insights for Na-ion
batteries development
P20
Alessandro Landi
Dipartimento di Chimica e
Biologia Adolfo Zambelli
Universitagrave di Salerno Via
Giovanni Paolo II I-84084
Fisciano (SA) Italy
Hole Mobility in Organic Semiconductors A Second-
Order Cumulant Approach
P21
Mariagrazia Fortino
Universitagrave di Modena e Reggio
Emilia Modena 41125 Italy
On the Simulation of Vibrationally Resolved Electronic
Spectra of medium-size molecules the case of Styryl
Substituted BODIPYs
P22
Marco Medves Dipdi Scienze Chimiche e
Farmaceutiche Universitagrave di
Trieste
Theoretical Study on the Circular Dichroism of Chiral
Bimetallic Clusters Ag-Au
P23
Jonathan Campeggio
Universitagrave degli Studi di Padova DiTe2 Calcolo del tensore di diffusione per molecole
flessibili
P24
Edoardo Jun
Mattioli
Chemistry Department ldquoG
Ciamicianrdquo University of Bologna
Computational Investigation of Competitive
Reaction Mechanisms inside Carbon Nanotubes
P25
Sergio Rampino
SMART Laboratory Scuola
Normale Superiore Piazza dei
Cavalieri 7 56126 Pisa
Combined Orbital-spaceReal-space Analysis of
Chemical Bonding through Virtual Reality
P26
Josephine Alba Dipdi Chimica Universitagrave di
Roma La Sapienza
Efficient and Accurate Modelling of Conformational
Transitions in proteins comparison between two Src
kinase proteins
P27
Abstracts delle conferenze su invito
I1
Solving the Schroumldinger equation in a box wavepackets and continuum states
Piero Decleva
DSCF Universitarsquo di Trieste declevaunitsit
ABSTRACT
Nelle molecole gli stati elettronici piursquo bassi decadono esponenzialmente con unrsquoestensione spaziale molto limitata Questo non ersquo piursquo vero per
- Stati Rydberg con alti numeri quantici - Stati del continuo - Pacchetti generati da impulsi elettromagnetici molto intensi
In tal caso le basi LCAO costruite da GTO o STO risultano inadeguate e sono necessari approcci alternativi sia funzioni di base diverse sia uso di griglie numeriche Per lo studio del continuo elettronico abbiamo da tempo sviluppato un set basato sullrsquouso di B-spline [1] come funzioni radiali adoperate nel modo LCAO convenzionale che si ersquo dimostrato assai flessibile e accurato Queste forniscono unrsquoeccellente rappresentazione delle soluzioni dellrsquoequazione di Schroumldinger allrsquointerno di una sfera di raggio prefissato arbitrario Calcoli dei parametri di fotoionizzazione molecolare a livello DFT [2] o TDDFT [3] forniscono generalmente risultati in buon accordo con lrsquoesperimento anche per sistemi relativamente grandi e per un gran numero di osservabili di fotoionizzazione sezioni drsquourto distribuzioni angolari di molecole con orientazione fissa o casuale parametri non-dipolari effetti di interferenza e diffrazione parametri chirali Ersquo stata anche applicata a fotoionizzazione risolta nel tempo da stati eccitati in esperimenti pump-probe e alla generazione di pacchetti di cationi da impulsi ultraveloci Piursquo recentemente la base ersquo stata applicata al calcolo di pacchetti drsquoonda eccitati da impulsi laser in regime non perturbativo Durante lrsquoimpulso lrsquoescursione dellrsquoelettrone puorsquo raggiungere migliaia di unitarsquo atomiche ma lrsquoapproccio ersquo numericamente molto stabile e si presta bene all propagazione del pacchetto per risoluzione dellrsquoequazione temporale Ersquo stata considerata la ionizzazione totale in funzione dellrsquoorientazione del campo rispetto alla molecola [4] il calcolo dello spettro di elettroni risolto in energia ed angolo attraverso la proiezione sugli autostati del continuo la rivelazione di pacchetti elettronici coerenti in esperimenti pump-probe agli attosecondi [5] la generazione di armoniche alte (HHG) [6] Verranno illustrati alcuni risultati recenti e discusse le linee di sviluppo
REFERENCES
1 H Bachau E Cormier P Decleva J E Hansen and F Martin ldquoApplications of B-splines in Atomic and Molecular Physicsrdquo
Reports on Progress in Physics 64 1815 (2001)
2 D Toffoli M Stener G Fronzoni and P Decleva ldquoConvergenge of the Multicenter B-spline DFT approach for the continuumrdquo
Chem Phys 276 25 (2002)
3 M Stener G Fronzoni and P Decleva ldquoTime-dependent density-functional theory for molecular photoionization with
noniterative algorithm and multicenter B-spline basis set CS2 and C6H6 case studiesrdquoJ Chem Phys 122 (2005) 234301
4 S Petretti YV Vanne A Saenz A Castro and P Decleva ldquoAlignment-Dependent Ionization of N2 O2 and CO2 in Intense
Laser Fieldsrdquo Phys Rev Letters 104 (2010) 223001
5 M Ruberti P Decleva and V Averbukh ldquoMulti-channel dynamics and correlation-driven inter-channel couplings in high
harmonic generation spectra of aligned CO2 molecule ab initio Time Dependent B-spline ADC ab initio analysisrdquo Phys Chem
Chem Phys 20 (2018) 8311
6 E Plesiat M Lara-Astiaso P Decleva A Palacios and F Martin ldquoReal-time determination of ultrafast charge dynamics in
tetrafluoromethane from attosecond pump-probe photoelectron spectroscopyrdquo Chem Eur J 242018 xxx
I2
Mixed quantumclassical description of the effects of nuclear motion in electronic spectroscopy and ultrafast
photophysics
Fabrizio Santoro1
1 ICCOM-CNR Area della Ricerca del CNR di Pisa Italy 2 Affiliazione 2
fabriziosantoroiccomcnrit
ABSTRACT
Quantum nuclear effects can play a relevant role in determining the shape of electronic spectra and the fate of the photoexcited dynamics in molecular systems Recent advancements in fully quantum vibronic approaches for the computation of spectra [12] and in quantum-dynamical (QD) approaches like those provided by the MCTDH method [3-5] allow an efficient description of such effects even in large systems if they are rigid (harmonic) and in gas phase Flexible systems or systems embedded in solvents or in heterogenoeus media possibly establishing with them specific interactions represent a challenge for fully quantum treatments of nuclear motions Classical and semi-classical trajectory based approaches are very well suited to deal with these cases but they neglect quantum nuclear effects We believe that the development of wise mixed quantum classical (MQC) approaches may represent a suitable framework to overcome some of these present limitations In this contribution we present our recent work in this field In electronic spectroscopy we introduced mixed schemes that separate fast and slow degrees of freedom (DoF) on the grounds of an adiabatic approximation and treat the fast DoF at quantum level and the slow ones (including the solvent) at classical level The spectra are then naturally expressed as an average of vibronic spectra involving along the fast DoF over the distribution of the classical DoF [5-7] Extending these ideas to ultrafast photophysical processes we recently proposed a MQC approach to introduce environmental dynamical effects in QD simulations In its simplest version all the solute degrees of freedom are represented by a wavepacket moving according to nonadiabatic quantum dynamics while the motion of an explicit solvent model is described by an ensemble of classical trajectories The core idea of the method is to describe the mutual coupling of the solute and solvent dynamics within a mean-field framework In this way the Hamiltonians of both the quantum and classical subsystems contain time-dependent terms due to the interaction with the other subset and the quantum and classical equations of motions are solved simultaneously We will discuss the potentialities limitations and possible perspectives of these methods with a number of test applications
REFERENCES
1 Barone V WIREs Comput Mol Sci 2016 6 86-110 2 Santoro F Jacquemin D WIREs Comput Mol Sci 2016 6 460-486 3 Wang H Thoss M J Chem Phys 2003 119 1289minus1299 Vendrell O Meyer H-D J Chem Phys 2011 134 044135 4 Beck M H J ckle A Worth G A Meyer H-D Phys Rep 2000 324 1minus105 5 CerezoJ Avila F Prampolini G Santoro F J Chem Theory Comput 2015 11 5810ndash5825
6 Cerezo J Mazzeo G Longhi G Abbate S Santoro F J Phys Chem Lett 2016 7 4891‐4897 7 Cerezo J Aranda D Avila F Mazzeo G Longhi G Abbate S Santoro F Chirality 2018 30 730ndash743 8 Cerezo J Liu Y Lin N Zhao X Improta R Santoro F J Chem Theory Comput 201814 820ndash832
I3
Defective but effective the role of defects on the electrocatalytic performance of oxide-based materials
for energy conversion
Ana B Muntildeoz Garciacutea1
1 Dipartimento di Fisica ldquoEttore Pancinirdquo Universitagrave di Napoli Federico II
Comp Univ Monte S Angelo via Cintia 21 80126 Napoli (Italia)
anabelenmunozgarciauninait
ABSTRACT
Ab initio simulations play an increasingly important role in materials sciences In the energy conversion scenario computational modeling can elucidate with atomic resolution the subtle composition-structure-property relationships behind the performance of functional materials and complex interfaces In heterogeneous electrocatalysis the underlying bulk and surface chargemass transport events are often strongly dependent on the presenceabsence of structural defects Thus a deep knowledge of defect chemistry is key for understanding tuning and optimizing the properties of different catalysts In particular this contribution will report recent advances in the DFT-based characterization of the role of defects in strongly correlated oxides as electrodes in electrocatalytic devices Three case studies will be presented (i) a new triple-conducting oxide based on Sr2Fe15Mo05O6 perovskite with promising bifunctional catalytic activity towards oxygen reduction and evolution reactions [1-3] (ii) Fe-doped ZrO2 for low temperature PEMFCs [4] and (iii) CuFeO2 delafossite for CO2 photoreduction [5] In all these cases we will discuss how surface oxygen vacancies -boosted by aliovalent doping- can improve the electrode performance and change product selectivity In conclusion this contribution will highlight the merits of computationally driven materials discovery in the context of energy conversion devices pointing out the importance of the necessary interplay between theory and experiment
REFERENCES
1 ABMG D Bugaris M Pavone J P Hodges A Huq F Chen H-C zur Loye E A Carter J Am Chem Soc 134 6826 (2012) 2 ABMG M Pavone Chem Mater 28 490 (2016) 3 ABMG M Pavone J Mater Chem A 5 12735 (2017) 4 P Madkikar D Menga G Harzer T Mittermeier A Siebel F E Wagner M Merz S Schuppler P Nagel ABMG M Pavone H A Gasteiger M Piana Submitted 5 J Gu A Wuttig J W Krizan Y Hu Z M Detweller R J Cava A B Bocarsly J Phys Chem C 117 12415 (2013)
I4
Solvent dynamics and energy transfer a real time description
Anna Painelli Francesco Di Maiolo
Dipartimento SCVSA Universitagrave di Parma annapainelliuniprit
ABSTRACT
Energy dissipation and relaxation phenomena are crucial to describe the dynamics of excited states The interaction of a molecule with the environment (the bath) is pivotal in this respect bringing theoretical chemistry towards the field of open quantum systems Several strategies are available to quantitatively describe the system-bath interaction most often based on the dynamics of the reduced density matrix Vibrational degrees of freedom must be explicitly described to address internal conversion and the huge dimension of the resulting basis imposes dramatic approximations to the calculation Here we face the problem adopting an essential state model (ESM) description of the molecular systems ESMs proved successful in describing low-energy linear and non-linear optical spectra of several families of organic dyes in terms of a minimal number of electronic states coupled to few effective vibrational modes ESMs successfully account for polar solvation and for intermolecular interactions in molecular aggregates and in energy transfer systems (1 2 3)
Here we present a dynamical non-adiabatic model for Resonance Energy Transfer (RET) Specifically we consider two dyes an energy donor (D) and an energy acceptor (A) Each dye corresponds to a push-pull chromophore described in terms of two electronic states coupled to a single effective vibration Accounting for dissipation phenomena within the Redfield approach we follow the real time dynamics of RET from the excited D towards A (Fig1 left panel) Moreover a newly derived multistate Redfield-Smoluchowski equation is used to investigate how the dynamical disorder induced by polar solvation affects RET (Fig1 right panel)
REFERENCES
1 F Terenziani A Painelli PhysChemChemPhys 17 13074-81 (2015) 2 C Sissa et al Phys Chem Chem Phys 2011 13 12734ndash12744 3 S Sanyal et al PhysChemChemPhys 2017 19 24979
Fig 1 Resonance
Energy Transfer in real
time Left Non-
adiabatic QUOTE
dynamics
following impulsive
excitation of the energy
donor the adiabatic
potential energy
surfaces are shown for
reference Right
temporal evolution of
the population of the
excited energy acceptor
in a frozen and liquid
polar solvent
I5
Towards an accurate computational photochemistry and photobiology the paradigmatic case of vision
Marco Garavelli1
1 Dipartimento di Chimica Industriale ldquoToso Montanarirdquo Viale del Risorgimento 4 40136 Bologna Italy 2 Affiliazione 2
marcogaravelliuniboit
ABSTRACT
The use of the computer to simulate light induced events in photoactive molecular materials has given access to a detailed description of the molecular motions and mechanisms underlying the reactivity of organic and bio-organic chromophores Thus different computational strategies and tools can now be operated like a ―virtual spectrometer to characterize and understand the photoinduced molecular deformation and reactivity of a given dye allowing for an accurate description of photochemicalphotobiological processes and a rational of the corresponding photophysical properties including time-resolved spectroscopy
This contribution reviews recent advances in this field by presenting methodological developments and applications in modeling the photophysicalphotochemical properties of organic chromophores and complex photoactive molecular architectures Retinal systems and visual proteins will be presented as a paradigmatic case [12] Hybrid QMMM calculations will be shown to be an elective tool for modeling photoinduced events and dynamics including tuningcontrolling effects of the environment For this purpose our new implementation of a general hybrid QMMM approach that is able to integrate some specialized softwares and acts as a flexible computational environment eventually allowing for so far inaccessible calculations (eg non-adiabatic molecular dynamics of unprecedented accuracy on large molecular materials) will be illustrated The information collected by these studies can be exploited for the design of novel photoactive molecular and soft materials including a novel paradigm of electrochromism for applications in a new generation of color tunable displays and e-ink devices Finally our latest achievements in developing (and modeling) non-linear bi-dimensional electronic spectroscopy as a novel diagnostic tool for tracking structuraldynamical problems in complex environments (eg biologically relevant systems such as proteins and DNA) will be presented [34]
REFERENCES
1 D Polli et al Nature 467 (2010) 440 2 B Demoulin et al JPCL 8 (2017) 4407 3 I Rivalta et al PCCP 16 (2014) 16865 4 I Rivalta et al JPCB 118 (2014) 8396
I6
Modellizzazione in fase condensata ad alte pressioni
Gianni Cardini
Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave di Firenze email giannicardiniunifiit
ABSTRACT
La modellizzazione delle proprietagrave strutturali e dinamiche di sistemi in fase condensata dipende essenzialmente dalla corretta descrizione del potenziale di interazione intermolecolare In simulazioni di dinamica molecolare1 si ricorre di solito a modelli di potenziale semi empirici o a metodi ab initio12 nella maggior parte dei casi basati sulla teoria del funzionale della densitagrave (DFT) Nel caso di sistemi sottoposti ad alte pressioni diventa cruciale una corretta descrizione delle interazioni a corto raggio e modelli che consentano eventualmente la rottura e formazione di legami chimici Verranno presentati alcuni risultati di simulazioni di dinamica molecolare ab initio con il metodo Car Parrinello Le simulazioni ab initio su fasi condensate basate su sistemi periodici sono dispendiose e pertanto condotte per tempi brevi e su campioni molto piccoli Inoltre nel campo delle alte pressioni gli sperimentali sono soliti interpretare i dati spettroscopici in termini di proprietagrave di singola molecola e necessitano di una modellizzazione possibilmente veloce per interpretare le loro misure Questo puograve essere ottenuto ricorrendo al metodo XP-PCM proposto da Cammi et al3 che consente di ottenere risultati qualitativi effettuando calcoli in condizioni estreme di pressione su singola molecola
REFERENCES
7 MP Allen amp DJ Tildesley Computer Simulation of Liquids Oxford University Press Oxford UK 2017 8 DMarx and J Hutter Ab Initio Molecular Dynamics Cambridge University Press Cambridge UK 2009 9 R Cammi et al Chem Phys 344 (2008) 135 R Cammi et al J ChemPhys 137 (2012) 154112
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
Abstracts delle conferenze su invito
I1
Solving the Schroumldinger equation in a box wavepackets and continuum states
Piero Decleva
DSCF Universitarsquo di Trieste declevaunitsit
ABSTRACT
Nelle molecole gli stati elettronici piursquo bassi decadono esponenzialmente con unrsquoestensione spaziale molto limitata Questo non ersquo piursquo vero per
- Stati Rydberg con alti numeri quantici - Stati del continuo - Pacchetti generati da impulsi elettromagnetici molto intensi
In tal caso le basi LCAO costruite da GTO o STO risultano inadeguate e sono necessari approcci alternativi sia funzioni di base diverse sia uso di griglie numeriche Per lo studio del continuo elettronico abbiamo da tempo sviluppato un set basato sullrsquouso di B-spline [1] come funzioni radiali adoperate nel modo LCAO convenzionale che si ersquo dimostrato assai flessibile e accurato Queste forniscono unrsquoeccellente rappresentazione delle soluzioni dellrsquoequazione di Schroumldinger allrsquointerno di una sfera di raggio prefissato arbitrario Calcoli dei parametri di fotoionizzazione molecolare a livello DFT [2] o TDDFT [3] forniscono generalmente risultati in buon accordo con lrsquoesperimento anche per sistemi relativamente grandi e per un gran numero di osservabili di fotoionizzazione sezioni drsquourto distribuzioni angolari di molecole con orientazione fissa o casuale parametri non-dipolari effetti di interferenza e diffrazione parametri chirali Ersquo stata anche applicata a fotoionizzazione risolta nel tempo da stati eccitati in esperimenti pump-probe e alla generazione di pacchetti di cationi da impulsi ultraveloci Piursquo recentemente la base ersquo stata applicata al calcolo di pacchetti drsquoonda eccitati da impulsi laser in regime non perturbativo Durante lrsquoimpulso lrsquoescursione dellrsquoelettrone puorsquo raggiungere migliaia di unitarsquo atomiche ma lrsquoapproccio ersquo numericamente molto stabile e si presta bene all propagazione del pacchetto per risoluzione dellrsquoequazione temporale Ersquo stata considerata la ionizzazione totale in funzione dellrsquoorientazione del campo rispetto alla molecola [4] il calcolo dello spettro di elettroni risolto in energia ed angolo attraverso la proiezione sugli autostati del continuo la rivelazione di pacchetti elettronici coerenti in esperimenti pump-probe agli attosecondi [5] la generazione di armoniche alte (HHG) [6] Verranno illustrati alcuni risultati recenti e discusse le linee di sviluppo
REFERENCES
1 H Bachau E Cormier P Decleva J E Hansen and F Martin ldquoApplications of B-splines in Atomic and Molecular Physicsrdquo
Reports on Progress in Physics 64 1815 (2001)
2 D Toffoli M Stener G Fronzoni and P Decleva ldquoConvergenge of the Multicenter B-spline DFT approach for the continuumrdquo
Chem Phys 276 25 (2002)
3 M Stener G Fronzoni and P Decleva ldquoTime-dependent density-functional theory for molecular photoionization with
noniterative algorithm and multicenter B-spline basis set CS2 and C6H6 case studiesrdquoJ Chem Phys 122 (2005) 234301
4 S Petretti YV Vanne A Saenz A Castro and P Decleva ldquoAlignment-Dependent Ionization of N2 O2 and CO2 in Intense
Laser Fieldsrdquo Phys Rev Letters 104 (2010) 223001
5 M Ruberti P Decleva and V Averbukh ldquoMulti-channel dynamics and correlation-driven inter-channel couplings in high
harmonic generation spectra of aligned CO2 molecule ab initio Time Dependent B-spline ADC ab initio analysisrdquo Phys Chem
Chem Phys 20 (2018) 8311
6 E Plesiat M Lara-Astiaso P Decleva A Palacios and F Martin ldquoReal-time determination of ultrafast charge dynamics in
tetrafluoromethane from attosecond pump-probe photoelectron spectroscopyrdquo Chem Eur J 242018 xxx
I2
Mixed quantumclassical description of the effects of nuclear motion in electronic spectroscopy and ultrafast
photophysics
Fabrizio Santoro1
1 ICCOM-CNR Area della Ricerca del CNR di Pisa Italy 2 Affiliazione 2
fabriziosantoroiccomcnrit
ABSTRACT
Quantum nuclear effects can play a relevant role in determining the shape of electronic spectra and the fate of the photoexcited dynamics in molecular systems Recent advancements in fully quantum vibronic approaches for the computation of spectra [12] and in quantum-dynamical (QD) approaches like those provided by the MCTDH method [3-5] allow an efficient description of such effects even in large systems if they are rigid (harmonic) and in gas phase Flexible systems or systems embedded in solvents or in heterogenoeus media possibly establishing with them specific interactions represent a challenge for fully quantum treatments of nuclear motions Classical and semi-classical trajectory based approaches are very well suited to deal with these cases but they neglect quantum nuclear effects We believe that the development of wise mixed quantum classical (MQC) approaches may represent a suitable framework to overcome some of these present limitations In this contribution we present our recent work in this field In electronic spectroscopy we introduced mixed schemes that separate fast and slow degrees of freedom (DoF) on the grounds of an adiabatic approximation and treat the fast DoF at quantum level and the slow ones (including the solvent) at classical level The spectra are then naturally expressed as an average of vibronic spectra involving along the fast DoF over the distribution of the classical DoF [5-7] Extending these ideas to ultrafast photophysical processes we recently proposed a MQC approach to introduce environmental dynamical effects in QD simulations In its simplest version all the solute degrees of freedom are represented by a wavepacket moving according to nonadiabatic quantum dynamics while the motion of an explicit solvent model is described by an ensemble of classical trajectories The core idea of the method is to describe the mutual coupling of the solute and solvent dynamics within a mean-field framework In this way the Hamiltonians of both the quantum and classical subsystems contain time-dependent terms due to the interaction with the other subset and the quantum and classical equations of motions are solved simultaneously We will discuss the potentialities limitations and possible perspectives of these methods with a number of test applications
REFERENCES
1 Barone V WIREs Comput Mol Sci 2016 6 86-110 2 Santoro F Jacquemin D WIREs Comput Mol Sci 2016 6 460-486 3 Wang H Thoss M J Chem Phys 2003 119 1289minus1299 Vendrell O Meyer H-D J Chem Phys 2011 134 044135 4 Beck M H J ckle A Worth G A Meyer H-D Phys Rep 2000 324 1minus105 5 CerezoJ Avila F Prampolini G Santoro F J Chem Theory Comput 2015 11 5810ndash5825
6 Cerezo J Mazzeo G Longhi G Abbate S Santoro F J Phys Chem Lett 2016 7 4891‐4897 7 Cerezo J Aranda D Avila F Mazzeo G Longhi G Abbate S Santoro F Chirality 2018 30 730ndash743 8 Cerezo J Liu Y Lin N Zhao X Improta R Santoro F J Chem Theory Comput 201814 820ndash832
I3
Defective but effective the role of defects on the electrocatalytic performance of oxide-based materials
for energy conversion
Ana B Muntildeoz Garciacutea1
1 Dipartimento di Fisica ldquoEttore Pancinirdquo Universitagrave di Napoli Federico II
Comp Univ Monte S Angelo via Cintia 21 80126 Napoli (Italia)
anabelenmunozgarciauninait
ABSTRACT
Ab initio simulations play an increasingly important role in materials sciences In the energy conversion scenario computational modeling can elucidate with atomic resolution the subtle composition-structure-property relationships behind the performance of functional materials and complex interfaces In heterogeneous electrocatalysis the underlying bulk and surface chargemass transport events are often strongly dependent on the presenceabsence of structural defects Thus a deep knowledge of defect chemistry is key for understanding tuning and optimizing the properties of different catalysts In particular this contribution will report recent advances in the DFT-based characterization of the role of defects in strongly correlated oxides as electrodes in electrocatalytic devices Three case studies will be presented (i) a new triple-conducting oxide based on Sr2Fe15Mo05O6 perovskite with promising bifunctional catalytic activity towards oxygen reduction and evolution reactions [1-3] (ii) Fe-doped ZrO2 for low temperature PEMFCs [4] and (iii) CuFeO2 delafossite for CO2 photoreduction [5] In all these cases we will discuss how surface oxygen vacancies -boosted by aliovalent doping- can improve the electrode performance and change product selectivity In conclusion this contribution will highlight the merits of computationally driven materials discovery in the context of energy conversion devices pointing out the importance of the necessary interplay between theory and experiment
REFERENCES
1 ABMG D Bugaris M Pavone J P Hodges A Huq F Chen H-C zur Loye E A Carter J Am Chem Soc 134 6826 (2012) 2 ABMG M Pavone Chem Mater 28 490 (2016) 3 ABMG M Pavone J Mater Chem A 5 12735 (2017) 4 P Madkikar D Menga G Harzer T Mittermeier A Siebel F E Wagner M Merz S Schuppler P Nagel ABMG M Pavone H A Gasteiger M Piana Submitted 5 J Gu A Wuttig J W Krizan Y Hu Z M Detweller R J Cava A B Bocarsly J Phys Chem C 117 12415 (2013)
I4
Solvent dynamics and energy transfer a real time description
Anna Painelli Francesco Di Maiolo
Dipartimento SCVSA Universitagrave di Parma annapainelliuniprit
ABSTRACT
Energy dissipation and relaxation phenomena are crucial to describe the dynamics of excited states The interaction of a molecule with the environment (the bath) is pivotal in this respect bringing theoretical chemistry towards the field of open quantum systems Several strategies are available to quantitatively describe the system-bath interaction most often based on the dynamics of the reduced density matrix Vibrational degrees of freedom must be explicitly described to address internal conversion and the huge dimension of the resulting basis imposes dramatic approximations to the calculation Here we face the problem adopting an essential state model (ESM) description of the molecular systems ESMs proved successful in describing low-energy linear and non-linear optical spectra of several families of organic dyes in terms of a minimal number of electronic states coupled to few effective vibrational modes ESMs successfully account for polar solvation and for intermolecular interactions in molecular aggregates and in energy transfer systems (1 2 3)
Here we present a dynamical non-adiabatic model for Resonance Energy Transfer (RET) Specifically we consider two dyes an energy donor (D) and an energy acceptor (A) Each dye corresponds to a push-pull chromophore described in terms of two electronic states coupled to a single effective vibration Accounting for dissipation phenomena within the Redfield approach we follow the real time dynamics of RET from the excited D towards A (Fig1 left panel) Moreover a newly derived multistate Redfield-Smoluchowski equation is used to investigate how the dynamical disorder induced by polar solvation affects RET (Fig1 right panel)
REFERENCES
1 F Terenziani A Painelli PhysChemChemPhys 17 13074-81 (2015) 2 C Sissa et al Phys Chem Chem Phys 2011 13 12734ndash12744 3 S Sanyal et al PhysChemChemPhys 2017 19 24979
Fig 1 Resonance
Energy Transfer in real
time Left Non-
adiabatic QUOTE
dynamics
following impulsive
excitation of the energy
donor the adiabatic
potential energy
surfaces are shown for
reference Right
temporal evolution of
the population of the
excited energy acceptor
in a frozen and liquid
polar solvent
I5
Towards an accurate computational photochemistry and photobiology the paradigmatic case of vision
Marco Garavelli1
1 Dipartimento di Chimica Industriale ldquoToso Montanarirdquo Viale del Risorgimento 4 40136 Bologna Italy 2 Affiliazione 2
marcogaravelliuniboit
ABSTRACT
The use of the computer to simulate light induced events in photoactive molecular materials has given access to a detailed description of the molecular motions and mechanisms underlying the reactivity of organic and bio-organic chromophores Thus different computational strategies and tools can now be operated like a ―virtual spectrometer to characterize and understand the photoinduced molecular deformation and reactivity of a given dye allowing for an accurate description of photochemicalphotobiological processes and a rational of the corresponding photophysical properties including time-resolved spectroscopy
This contribution reviews recent advances in this field by presenting methodological developments and applications in modeling the photophysicalphotochemical properties of organic chromophores and complex photoactive molecular architectures Retinal systems and visual proteins will be presented as a paradigmatic case [12] Hybrid QMMM calculations will be shown to be an elective tool for modeling photoinduced events and dynamics including tuningcontrolling effects of the environment For this purpose our new implementation of a general hybrid QMMM approach that is able to integrate some specialized softwares and acts as a flexible computational environment eventually allowing for so far inaccessible calculations (eg non-adiabatic molecular dynamics of unprecedented accuracy on large molecular materials) will be illustrated The information collected by these studies can be exploited for the design of novel photoactive molecular and soft materials including a novel paradigm of electrochromism for applications in a new generation of color tunable displays and e-ink devices Finally our latest achievements in developing (and modeling) non-linear bi-dimensional electronic spectroscopy as a novel diagnostic tool for tracking structuraldynamical problems in complex environments (eg biologically relevant systems such as proteins and DNA) will be presented [34]
REFERENCES
1 D Polli et al Nature 467 (2010) 440 2 B Demoulin et al JPCL 8 (2017) 4407 3 I Rivalta et al PCCP 16 (2014) 16865 4 I Rivalta et al JPCB 118 (2014) 8396
I6
Modellizzazione in fase condensata ad alte pressioni
Gianni Cardini
Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave di Firenze email giannicardiniunifiit
ABSTRACT
La modellizzazione delle proprietagrave strutturali e dinamiche di sistemi in fase condensata dipende essenzialmente dalla corretta descrizione del potenziale di interazione intermolecolare In simulazioni di dinamica molecolare1 si ricorre di solito a modelli di potenziale semi empirici o a metodi ab initio12 nella maggior parte dei casi basati sulla teoria del funzionale della densitagrave (DFT) Nel caso di sistemi sottoposti ad alte pressioni diventa cruciale una corretta descrizione delle interazioni a corto raggio e modelli che consentano eventualmente la rottura e formazione di legami chimici Verranno presentati alcuni risultati di simulazioni di dinamica molecolare ab initio con il metodo Car Parrinello Le simulazioni ab initio su fasi condensate basate su sistemi periodici sono dispendiose e pertanto condotte per tempi brevi e su campioni molto piccoli Inoltre nel campo delle alte pressioni gli sperimentali sono soliti interpretare i dati spettroscopici in termini di proprietagrave di singola molecola e necessitano di una modellizzazione possibilmente veloce per interpretare le loro misure Questo puograve essere ottenuto ricorrendo al metodo XP-PCM proposto da Cammi et al3 che consente di ottenere risultati qualitativi effettuando calcoli in condizioni estreme di pressione su singola molecola
REFERENCES
7 MP Allen amp DJ Tildesley Computer Simulation of Liquids Oxford University Press Oxford UK 2017 8 DMarx and J Hutter Ab Initio Molecular Dynamics Cambridge University Press Cambridge UK 2009 9 R Cammi et al Chem Phys 344 (2008) 135 R Cammi et al J ChemPhys 137 (2012) 154112
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
I1
Solving the Schroumldinger equation in a box wavepackets and continuum states
Piero Decleva
DSCF Universitarsquo di Trieste declevaunitsit
ABSTRACT
Nelle molecole gli stati elettronici piursquo bassi decadono esponenzialmente con unrsquoestensione spaziale molto limitata Questo non ersquo piursquo vero per
- Stati Rydberg con alti numeri quantici - Stati del continuo - Pacchetti generati da impulsi elettromagnetici molto intensi
In tal caso le basi LCAO costruite da GTO o STO risultano inadeguate e sono necessari approcci alternativi sia funzioni di base diverse sia uso di griglie numeriche Per lo studio del continuo elettronico abbiamo da tempo sviluppato un set basato sullrsquouso di B-spline [1] come funzioni radiali adoperate nel modo LCAO convenzionale che si ersquo dimostrato assai flessibile e accurato Queste forniscono unrsquoeccellente rappresentazione delle soluzioni dellrsquoequazione di Schroumldinger allrsquointerno di una sfera di raggio prefissato arbitrario Calcoli dei parametri di fotoionizzazione molecolare a livello DFT [2] o TDDFT [3] forniscono generalmente risultati in buon accordo con lrsquoesperimento anche per sistemi relativamente grandi e per un gran numero di osservabili di fotoionizzazione sezioni drsquourto distribuzioni angolari di molecole con orientazione fissa o casuale parametri non-dipolari effetti di interferenza e diffrazione parametri chirali Ersquo stata anche applicata a fotoionizzazione risolta nel tempo da stati eccitati in esperimenti pump-probe e alla generazione di pacchetti di cationi da impulsi ultraveloci Piursquo recentemente la base ersquo stata applicata al calcolo di pacchetti drsquoonda eccitati da impulsi laser in regime non perturbativo Durante lrsquoimpulso lrsquoescursione dellrsquoelettrone puorsquo raggiungere migliaia di unitarsquo atomiche ma lrsquoapproccio ersquo numericamente molto stabile e si presta bene all propagazione del pacchetto per risoluzione dellrsquoequazione temporale Ersquo stata considerata la ionizzazione totale in funzione dellrsquoorientazione del campo rispetto alla molecola [4] il calcolo dello spettro di elettroni risolto in energia ed angolo attraverso la proiezione sugli autostati del continuo la rivelazione di pacchetti elettronici coerenti in esperimenti pump-probe agli attosecondi [5] la generazione di armoniche alte (HHG) [6] Verranno illustrati alcuni risultati recenti e discusse le linee di sviluppo
REFERENCES
1 H Bachau E Cormier P Decleva J E Hansen and F Martin ldquoApplications of B-splines in Atomic and Molecular Physicsrdquo
Reports on Progress in Physics 64 1815 (2001)
2 D Toffoli M Stener G Fronzoni and P Decleva ldquoConvergenge of the Multicenter B-spline DFT approach for the continuumrdquo
Chem Phys 276 25 (2002)
3 M Stener G Fronzoni and P Decleva ldquoTime-dependent density-functional theory for molecular photoionization with
noniterative algorithm and multicenter B-spline basis set CS2 and C6H6 case studiesrdquoJ Chem Phys 122 (2005) 234301
4 S Petretti YV Vanne A Saenz A Castro and P Decleva ldquoAlignment-Dependent Ionization of N2 O2 and CO2 in Intense
Laser Fieldsrdquo Phys Rev Letters 104 (2010) 223001
5 M Ruberti P Decleva and V Averbukh ldquoMulti-channel dynamics and correlation-driven inter-channel couplings in high
harmonic generation spectra of aligned CO2 molecule ab initio Time Dependent B-spline ADC ab initio analysisrdquo Phys Chem
Chem Phys 20 (2018) 8311
6 E Plesiat M Lara-Astiaso P Decleva A Palacios and F Martin ldquoReal-time determination of ultrafast charge dynamics in
tetrafluoromethane from attosecond pump-probe photoelectron spectroscopyrdquo Chem Eur J 242018 xxx
I2
Mixed quantumclassical description of the effects of nuclear motion in electronic spectroscopy and ultrafast
photophysics
Fabrizio Santoro1
1 ICCOM-CNR Area della Ricerca del CNR di Pisa Italy 2 Affiliazione 2
fabriziosantoroiccomcnrit
ABSTRACT
Quantum nuclear effects can play a relevant role in determining the shape of electronic spectra and the fate of the photoexcited dynamics in molecular systems Recent advancements in fully quantum vibronic approaches for the computation of spectra [12] and in quantum-dynamical (QD) approaches like those provided by the MCTDH method [3-5] allow an efficient description of such effects even in large systems if they are rigid (harmonic) and in gas phase Flexible systems or systems embedded in solvents or in heterogenoeus media possibly establishing with them specific interactions represent a challenge for fully quantum treatments of nuclear motions Classical and semi-classical trajectory based approaches are very well suited to deal with these cases but they neglect quantum nuclear effects We believe that the development of wise mixed quantum classical (MQC) approaches may represent a suitable framework to overcome some of these present limitations In this contribution we present our recent work in this field In electronic spectroscopy we introduced mixed schemes that separate fast and slow degrees of freedom (DoF) on the grounds of an adiabatic approximation and treat the fast DoF at quantum level and the slow ones (including the solvent) at classical level The spectra are then naturally expressed as an average of vibronic spectra involving along the fast DoF over the distribution of the classical DoF [5-7] Extending these ideas to ultrafast photophysical processes we recently proposed a MQC approach to introduce environmental dynamical effects in QD simulations In its simplest version all the solute degrees of freedom are represented by a wavepacket moving according to nonadiabatic quantum dynamics while the motion of an explicit solvent model is described by an ensemble of classical trajectories The core idea of the method is to describe the mutual coupling of the solute and solvent dynamics within a mean-field framework In this way the Hamiltonians of both the quantum and classical subsystems contain time-dependent terms due to the interaction with the other subset and the quantum and classical equations of motions are solved simultaneously We will discuss the potentialities limitations and possible perspectives of these methods with a number of test applications
REFERENCES
1 Barone V WIREs Comput Mol Sci 2016 6 86-110 2 Santoro F Jacquemin D WIREs Comput Mol Sci 2016 6 460-486 3 Wang H Thoss M J Chem Phys 2003 119 1289minus1299 Vendrell O Meyer H-D J Chem Phys 2011 134 044135 4 Beck M H J ckle A Worth G A Meyer H-D Phys Rep 2000 324 1minus105 5 CerezoJ Avila F Prampolini G Santoro F J Chem Theory Comput 2015 11 5810ndash5825
6 Cerezo J Mazzeo G Longhi G Abbate S Santoro F J Phys Chem Lett 2016 7 4891‐4897 7 Cerezo J Aranda D Avila F Mazzeo G Longhi G Abbate S Santoro F Chirality 2018 30 730ndash743 8 Cerezo J Liu Y Lin N Zhao X Improta R Santoro F J Chem Theory Comput 201814 820ndash832
I3
Defective but effective the role of defects on the electrocatalytic performance of oxide-based materials
for energy conversion
Ana B Muntildeoz Garciacutea1
1 Dipartimento di Fisica ldquoEttore Pancinirdquo Universitagrave di Napoli Federico II
Comp Univ Monte S Angelo via Cintia 21 80126 Napoli (Italia)
anabelenmunozgarciauninait
ABSTRACT
Ab initio simulations play an increasingly important role in materials sciences In the energy conversion scenario computational modeling can elucidate with atomic resolution the subtle composition-structure-property relationships behind the performance of functional materials and complex interfaces In heterogeneous electrocatalysis the underlying bulk and surface chargemass transport events are often strongly dependent on the presenceabsence of structural defects Thus a deep knowledge of defect chemistry is key for understanding tuning and optimizing the properties of different catalysts In particular this contribution will report recent advances in the DFT-based characterization of the role of defects in strongly correlated oxides as electrodes in electrocatalytic devices Three case studies will be presented (i) a new triple-conducting oxide based on Sr2Fe15Mo05O6 perovskite with promising bifunctional catalytic activity towards oxygen reduction and evolution reactions [1-3] (ii) Fe-doped ZrO2 for low temperature PEMFCs [4] and (iii) CuFeO2 delafossite for CO2 photoreduction [5] In all these cases we will discuss how surface oxygen vacancies -boosted by aliovalent doping- can improve the electrode performance and change product selectivity In conclusion this contribution will highlight the merits of computationally driven materials discovery in the context of energy conversion devices pointing out the importance of the necessary interplay between theory and experiment
REFERENCES
1 ABMG D Bugaris M Pavone J P Hodges A Huq F Chen H-C zur Loye E A Carter J Am Chem Soc 134 6826 (2012) 2 ABMG M Pavone Chem Mater 28 490 (2016) 3 ABMG M Pavone J Mater Chem A 5 12735 (2017) 4 P Madkikar D Menga G Harzer T Mittermeier A Siebel F E Wagner M Merz S Schuppler P Nagel ABMG M Pavone H A Gasteiger M Piana Submitted 5 J Gu A Wuttig J W Krizan Y Hu Z M Detweller R J Cava A B Bocarsly J Phys Chem C 117 12415 (2013)
I4
Solvent dynamics and energy transfer a real time description
Anna Painelli Francesco Di Maiolo
Dipartimento SCVSA Universitagrave di Parma annapainelliuniprit
ABSTRACT
Energy dissipation and relaxation phenomena are crucial to describe the dynamics of excited states The interaction of a molecule with the environment (the bath) is pivotal in this respect bringing theoretical chemistry towards the field of open quantum systems Several strategies are available to quantitatively describe the system-bath interaction most often based on the dynamics of the reduced density matrix Vibrational degrees of freedom must be explicitly described to address internal conversion and the huge dimension of the resulting basis imposes dramatic approximations to the calculation Here we face the problem adopting an essential state model (ESM) description of the molecular systems ESMs proved successful in describing low-energy linear and non-linear optical spectra of several families of organic dyes in terms of a minimal number of electronic states coupled to few effective vibrational modes ESMs successfully account for polar solvation and for intermolecular interactions in molecular aggregates and in energy transfer systems (1 2 3)
Here we present a dynamical non-adiabatic model for Resonance Energy Transfer (RET) Specifically we consider two dyes an energy donor (D) and an energy acceptor (A) Each dye corresponds to a push-pull chromophore described in terms of two electronic states coupled to a single effective vibration Accounting for dissipation phenomena within the Redfield approach we follow the real time dynamics of RET from the excited D towards A (Fig1 left panel) Moreover a newly derived multistate Redfield-Smoluchowski equation is used to investigate how the dynamical disorder induced by polar solvation affects RET (Fig1 right panel)
REFERENCES
1 F Terenziani A Painelli PhysChemChemPhys 17 13074-81 (2015) 2 C Sissa et al Phys Chem Chem Phys 2011 13 12734ndash12744 3 S Sanyal et al PhysChemChemPhys 2017 19 24979
Fig 1 Resonance
Energy Transfer in real
time Left Non-
adiabatic QUOTE
dynamics
following impulsive
excitation of the energy
donor the adiabatic
potential energy
surfaces are shown for
reference Right
temporal evolution of
the population of the
excited energy acceptor
in a frozen and liquid
polar solvent
I5
Towards an accurate computational photochemistry and photobiology the paradigmatic case of vision
Marco Garavelli1
1 Dipartimento di Chimica Industriale ldquoToso Montanarirdquo Viale del Risorgimento 4 40136 Bologna Italy 2 Affiliazione 2
marcogaravelliuniboit
ABSTRACT
The use of the computer to simulate light induced events in photoactive molecular materials has given access to a detailed description of the molecular motions and mechanisms underlying the reactivity of organic and bio-organic chromophores Thus different computational strategies and tools can now be operated like a ―virtual spectrometer to characterize and understand the photoinduced molecular deformation and reactivity of a given dye allowing for an accurate description of photochemicalphotobiological processes and a rational of the corresponding photophysical properties including time-resolved spectroscopy
This contribution reviews recent advances in this field by presenting methodological developments and applications in modeling the photophysicalphotochemical properties of organic chromophores and complex photoactive molecular architectures Retinal systems and visual proteins will be presented as a paradigmatic case [12] Hybrid QMMM calculations will be shown to be an elective tool for modeling photoinduced events and dynamics including tuningcontrolling effects of the environment For this purpose our new implementation of a general hybrid QMMM approach that is able to integrate some specialized softwares and acts as a flexible computational environment eventually allowing for so far inaccessible calculations (eg non-adiabatic molecular dynamics of unprecedented accuracy on large molecular materials) will be illustrated The information collected by these studies can be exploited for the design of novel photoactive molecular and soft materials including a novel paradigm of electrochromism for applications in a new generation of color tunable displays and e-ink devices Finally our latest achievements in developing (and modeling) non-linear bi-dimensional electronic spectroscopy as a novel diagnostic tool for tracking structuraldynamical problems in complex environments (eg biologically relevant systems such as proteins and DNA) will be presented [34]
REFERENCES
1 D Polli et al Nature 467 (2010) 440 2 B Demoulin et al JPCL 8 (2017) 4407 3 I Rivalta et al PCCP 16 (2014) 16865 4 I Rivalta et al JPCB 118 (2014) 8396
I6
Modellizzazione in fase condensata ad alte pressioni
Gianni Cardini
Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave di Firenze email giannicardiniunifiit
ABSTRACT
La modellizzazione delle proprietagrave strutturali e dinamiche di sistemi in fase condensata dipende essenzialmente dalla corretta descrizione del potenziale di interazione intermolecolare In simulazioni di dinamica molecolare1 si ricorre di solito a modelli di potenziale semi empirici o a metodi ab initio12 nella maggior parte dei casi basati sulla teoria del funzionale della densitagrave (DFT) Nel caso di sistemi sottoposti ad alte pressioni diventa cruciale una corretta descrizione delle interazioni a corto raggio e modelli che consentano eventualmente la rottura e formazione di legami chimici Verranno presentati alcuni risultati di simulazioni di dinamica molecolare ab initio con il metodo Car Parrinello Le simulazioni ab initio su fasi condensate basate su sistemi periodici sono dispendiose e pertanto condotte per tempi brevi e su campioni molto piccoli Inoltre nel campo delle alte pressioni gli sperimentali sono soliti interpretare i dati spettroscopici in termini di proprietagrave di singola molecola e necessitano di una modellizzazione possibilmente veloce per interpretare le loro misure Questo puograve essere ottenuto ricorrendo al metodo XP-PCM proposto da Cammi et al3 che consente di ottenere risultati qualitativi effettuando calcoli in condizioni estreme di pressione su singola molecola
REFERENCES
7 MP Allen amp DJ Tildesley Computer Simulation of Liquids Oxford University Press Oxford UK 2017 8 DMarx and J Hutter Ab Initio Molecular Dynamics Cambridge University Press Cambridge UK 2009 9 R Cammi et al Chem Phys 344 (2008) 135 R Cammi et al J ChemPhys 137 (2012) 154112
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
I2
Mixed quantumclassical description of the effects of nuclear motion in electronic spectroscopy and ultrafast
photophysics
Fabrizio Santoro1
1 ICCOM-CNR Area della Ricerca del CNR di Pisa Italy 2 Affiliazione 2
fabriziosantoroiccomcnrit
ABSTRACT
Quantum nuclear effects can play a relevant role in determining the shape of electronic spectra and the fate of the photoexcited dynamics in molecular systems Recent advancements in fully quantum vibronic approaches for the computation of spectra [12] and in quantum-dynamical (QD) approaches like those provided by the MCTDH method [3-5] allow an efficient description of such effects even in large systems if they are rigid (harmonic) and in gas phase Flexible systems or systems embedded in solvents or in heterogenoeus media possibly establishing with them specific interactions represent a challenge for fully quantum treatments of nuclear motions Classical and semi-classical trajectory based approaches are very well suited to deal with these cases but they neglect quantum nuclear effects We believe that the development of wise mixed quantum classical (MQC) approaches may represent a suitable framework to overcome some of these present limitations In this contribution we present our recent work in this field In electronic spectroscopy we introduced mixed schemes that separate fast and slow degrees of freedom (DoF) on the grounds of an adiabatic approximation and treat the fast DoF at quantum level and the slow ones (including the solvent) at classical level The spectra are then naturally expressed as an average of vibronic spectra involving along the fast DoF over the distribution of the classical DoF [5-7] Extending these ideas to ultrafast photophysical processes we recently proposed a MQC approach to introduce environmental dynamical effects in QD simulations In its simplest version all the solute degrees of freedom are represented by a wavepacket moving according to nonadiabatic quantum dynamics while the motion of an explicit solvent model is described by an ensemble of classical trajectories The core idea of the method is to describe the mutual coupling of the solute and solvent dynamics within a mean-field framework In this way the Hamiltonians of both the quantum and classical subsystems contain time-dependent terms due to the interaction with the other subset and the quantum and classical equations of motions are solved simultaneously We will discuss the potentialities limitations and possible perspectives of these methods with a number of test applications
REFERENCES
1 Barone V WIREs Comput Mol Sci 2016 6 86-110 2 Santoro F Jacquemin D WIREs Comput Mol Sci 2016 6 460-486 3 Wang H Thoss M J Chem Phys 2003 119 1289minus1299 Vendrell O Meyer H-D J Chem Phys 2011 134 044135 4 Beck M H J ckle A Worth G A Meyer H-D Phys Rep 2000 324 1minus105 5 CerezoJ Avila F Prampolini G Santoro F J Chem Theory Comput 2015 11 5810ndash5825
6 Cerezo J Mazzeo G Longhi G Abbate S Santoro F J Phys Chem Lett 2016 7 4891‐4897 7 Cerezo J Aranda D Avila F Mazzeo G Longhi G Abbate S Santoro F Chirality 2018 30 730ndash743 8 Cerezo J Liu Y Lin N Zhao X Improta R Santoro F J Chem Theory Comput 201814 820ndash832
I3
Defective but effective the role of defects on the electrocatalytic performance of oxide-based materials
for energy conversion
Ana B Muntildeoz Garciacutea1
1 Dipartimento di Fisica ldquoEttore Pancinirdquo Universitagrave di Napoli Federico II
Comp Univ Monte S Angelo via Cintia 21 80126 Napoli (Italia)
anabelenmunozgarciauninait
ABSTRACT
Ab initio simulations play an increasingly important role in materials sciences In the energy conversion scenario computational modeling can elucidate with atomic resolution the subtle composition-structure-property relationships behind the performance of functional materials and complex interfaces In heterogeneous electrocatalysis the underlying bulk and surface chargemass transport events are often strongly dependent on the presenceabsence of structural defects Thus a deep knowledge of defect chemistry is key for understanding tuning and optimizing the properties of different catalysts In particular this contribution will report recent advances in the DFT-based characterization of the role of defects in strongly correlated oxides as electrodes in electrocatalytic devices Three case studies will be presented (i) a new triple-conducting oxide based on Sr2Fe15Mo05O6 perovskite with promising bifunctional catalytic activity towards oxygen reduction and evolution reactions [1-3] (ii) Fe-doped ZrO2 for low temperature PEMFCs [4] and (iii) CuFeO2 delafossite for CO2 photoreduction [5] In all these cases we will discuss how surface oxygen vacancies -boosted by aliovalent doping- can improve the electrode performance and change product selectivity In conclusion this contribution will highlight the merits of computationally driven materials discovery in the context of energy conversion devices pointing out the importance of the necessary interplay between theory and experiment
REFERENCES
1 ABMG D Bugaris M Pavone J P Hodges A Huq F Chen H-C zur Loye E A Carter J Am Chem Soc 134 6826 (2012) 2 ABMG M Pavone Chem Mater 28 490 (2016) 3 ABMG M Pavone J Mater Chem A 5 12735 (2017) 4 P Madkikar D Menga G Harzer T Mittermeier A Siebel F E Wagner M Merz S Schuppler P Nagel ABMG M Pavone H A Gasteiger M Piana Submitted 5 J Gu A Wuttig J W Krizan Y Hu Z M Detweller R J Cava A B Bocarsly J Phys Chem C 117 12415 (2013)
I4
Solvent dynamics and energy transfer a real time description
Anna Painelli Francesco Di Maiolo
Dipartimento SCVSA Universitagrave di Parma annapainelliuniprit
ABSTRACT
Energy dissipation and relaxation phenomena are crucial to describe the dynamics of excited states The interaction of a molecule with the environment (the bath) is pivotal in this respect bringing theoretical chemistry towards the field of open quantum systems Several strategies are available to quantitatively describe the system-bath interaction most often based on the dynamics of the reduced density matrix Vibrational degrees of freedom must be explicitly described to address internal conversion and the huge dimension of the resulting basis imposes dramatic approximations to the calculation Here we face the problem adopting an essential state model (ESM) description of the molecular systems ESMs proved successful in describing low-energy linear and non-linear optical spectra of several families of organic dyes in terms of a minimal number of electronic states coupled to few effective vibrational modes ESMs successfully account for polar solvation and for intermolecular interactions in molecular aggregates and in energy transfer systems (1 2 3)
Here we present a dynamical non-adiabatic model for Resonance Energy Transfer (RET) Specifically we consider two dyes an energy donor (D) and an energy acceptor (A) Each dye corresponds to a push-pull chromophore described in terms of two electronic states coupled to a single effective vibration Accounting for dissipation phenomena within the Redfield approach we follow the real time dynamics of RET from the excited D towards A (Fig1 left panel) Moreover a newly derived multistate Redfield-Smoluchowski equation is used to investigate how the dynamical disorder induced by polar solvation affects RET (Fig1 right panel)
REFERENCES
1 F Terenziani A Painelli PhysChemChemPhys 17 13074-81 (2015) 2 C Sissa et al Phys Chem Chem Phys 2011 13 12734ndash12744 3 S Sanyal et al PhysChemChemPhys 2017 19 24979
Fig 1 Resonance
Energy Transfer in real
time Left Non-
adiabatic QUOTE
dynamics
following impulsive
excitation of the energy
donor the adiabatic
potential energy
surfaces are shown for
reference Right
temporal evolution of
the population of the
excited energy acceptor
in a frozen and liquid
polar solvent
I5
Towards an accurate computational photochemistry and photobiology the paradigmatic case of vision
Marco Garavelli1
1 Dipartimento di Chimica Industriale ldquoToso Montanarirdquo Viale del Risorgimento 4 40136 Bologna Italy 2 Affiliazione 2
marcogaravelliuniboit
ABSTRACT
The use of the computer to simulate light induced events in photoactive molecular materials has given access to a detailed description of the molecular motions and mechanisms underlying the reactivity of organic and bio-organic chromophores Thus different computational strategies and tools can now be operated like a ―virtual spectrometer to characterize and understand the photoinduced molecular deformation and reactivity of a given dye allowing for an accurate description of photochemicalphotobiological processes and a rational of the corresponding photophysical properties including time-resolved spectroscopy
This contribution reviews recent advances in this field by presenting methodological developments and applications in modeling the photophysicalphotochemical properties of organic chromophores and complex photoactive molecular architectures Retinal systems and visual proteins will be presented as a paradigmatic case [12] Hybrid QMMM calculations will be shown to be an elective tool for modeling photoinduced events and dynamics including tuningcontrolling effects of the environment For this purpose our new implementation of a general hybrid QMMM approach that is able to integrate some specialized softwares and acts as a flexible computational environment eventually allowing for so far inaccessible calculations (eg non-adiabatic molecular dynamics of unprecedented accuracy on large molecular materials) will be illustrated The information collected by these studies can be exploited for the design of novel photoactive molecular and soft materials including a novel paradigm of electrochromism for applications in a new generation of color tunable displays and e-ink devices Finally our latest achievements in developing (and modeling) non-linear bi-dimensional electronic spectroscopy as a novel diagnostic tool for tracking structuraldynamical problems in complex environments (eg biologically relevant systems such as proteins and DNA) will be presented [34]
REFERENCES
1 D Polli et al Nature 467 (2010) 440 2 B Demoulin et al JPCL 8 (2017) 4407 3 I Rivalta et al PCCP 16 (2014) 16865 4 I Rivalta et al JPCB 118 (2014) 8396
I6
Modellizzazione in fase condensata ad alte pressioni
Gianni Cardini
Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave di Firenze email giannicardiniunifiit
ABSTRACT
La modellizzazione delle proprietagrave strutturali e dinamiche di sistemi in fase condensata dipende essenzialmente dalla corretta descrizione del potenziale di interazione intermolecolare In simulazioni di dinamica molecolare1 si ricorre di solito a modelli di potenziale semi empirici o a metodi ab initio12 nella maggior parte dei casi basati sulla teoria del funzionale della densitagrave (DFT) Nel caso di sistemi sottoposti ad alte pressioni diventa cruciale una corretta descrizione delle interazioni a corto raggio e modelli che consentano eventualmente la rottura e formazione di legami chimici Verranno presentati alcuni risultati di simulazioni di dinamica molecolare ab initio con il metodo Car Parrinello Le simulazioni ab initio su fasi condensate basate su sistemi periodici sono dispendiose e pertanto condotte per tempi brevi e su campioni molto piccoli Inoltre nel campo delle alte pressioni gli sperimentali sono soliti interpretare i dati spettroscopici in termini di proprietagrave di singola molecola e necessitano di una modellizzazione possibilmente veloce per interpretare le loro misure Questo puograve essere ottenuto ricorrendo al metodo XP-PCM proposto da Cammi et al3 che consente di ottenere risultati qualitativi effettuando calcoli in condizioni estreme di pressione su singola molecola
REFERENCES
7 MP Allen amp DJ Tildesley Computer Simulation of Liquids Oxford University Press Oxford UK 2017 8 DMarx and J Hutter Ab Initio Molecular Dynamics Cambridge University Press Cambridge UK 2009 9 R Cammi et al Chem Phys 344 (2008) 135 R Cammi et al J ChemPhys 137 (2012) 154112
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
I3
Defective but effective the role of defects on the electrocatalytic performance of oxide-based materials
for energy conversion
Ana B Muntildeoz Garciacutea1
1 Dipartimento di Fisica ldquoEttore Pancinirdquo Universitagrave di Napoli Federico II
Comp Univ Monte S Angelo via Cintia 21 80126 Napoli (Italia)
anabelenmunozgarciauninait
ABSTRACT
Ab initio simulations play an increasingly important role in materials sciences In the energy conversion scenario computational modeling can elucidate with atomic resolution the subtle composition-structure-property relationships behind the performance of functional materials and complex interfaces In heterogeneous electrocatalysis the underlying bulk and surface chargemass transport events are often strongly dependent on the presenceabsence of structural defects Thus a deep knowledge of defect chemistry is key for understanding tuning and optimizing the properties of different catalysts In particular this contribution will report recent advances in the DFT-based characterization of the role of defects in strongly correlated oxides as electrodes in electrocatalytic devices Three case studies will be presented (i) a new triple-conducting oxide based on Sr2Fe15Mo05O6 perovskite with promising bifunctional catalytic activity towards oxygen reduction and evolution reactions [1-3] (ii) Fe-doped ZrO2 for low temperature PEMFCs [4] and (iii) CuFeO2 delafossite for CO2 photoreduction [5] In all these cases we will discuss how surface oxygen vacancies -boosted by aliovalent doping- can improve the electrode performance and change product selectivity In conclusion this contribution will highlight the merits of computationally driven materials discovery in the context of energy conversion devices pointing out the importance of the necessary interplay between theory and experiment
REFERENCES
1 ABMG D Bugaris M Pavone J P Hodges A Huq F Chen H-C zur Loye E A Carter J Am Chem Soc 134 6826 (2012) 2 ABMG M Pavone Chem Mater 28 490 (2016) 3 ABMG M Pavone J Mater Chem A 5 12735 (2017) 4 P Madkikar D Menga G Harzer T Mittermeier A Siebel F E Wagner M Merz S Schuppler P Nagel ABMG M Pavone H A Gasteiger M Piana Submitted 5 J Gu A Wuttig J W Krizan Y Hu Z M Detweller R J Cava A B Bocarsly J Phys Chem C 117 12415 (2013)
I4
Solvent dynamics and energy transfer a real time description
Anna Painelli Francesco Di Maiolo
Dipartimento SCVSA Universitagrave di Parma annapainelliuniprit
ABSTRACT
Energy dissipation and relaxation phenomena are crucial to describe the dynamics of excited states The interaction of a molecule with the environment (the bath) is pivotal in this respect bringing theoretical chemistry towards the field of open quantum systems Several strategies are available to quantitatively describe the system-bath interaction most often based on the dynamics of the reduced density matrix Vibrational degrees of freedom must be explicitly described to address internal conversion and the huge dimension of the resulting basis imposes dramatic approximations to the calculation Here we face the problem adopting an essential state model (ESM) description of the molecular systems ESMs proved successful in describing low-energy linear and non-linear optical spectra of several families of organic dyes in terms of a minimal number of electronic states coupled to few effective vibrational modes ESMs successfully account for polar solvation and for intermolecular interactions in molecular aggregates and in energy transfer systems (1 2 3)
Here we present a dynamical non-adiabatic model for Resonance Energy Transfer (RET) Specifically we consider two dyes an energy donor (D) and an energy acceptor (A) Each dye corresponds to a push-pull chromophore described in terms of two electronic states coupled to a single effective vibration Accounting for dissipation phenomena within the Redfield approach we follow the real time dynamics of RET from the excited D towards A (Fig1 left panel) Moreover a newly derived multistate Redfield-Smoluchowski equation is used to investigate how the dynamical disorder induced by polar solvation affects RET (Fig1 right panel)
REFERENCES
1 F Terenziani A Painelli PhysChemChemPhys 17 13074-81 (2015) 2 C Sissa et al Phys Chem Chem Phys 2011 13 12734ndash12744 3 S Sanyal et al PhysChemChemPhys 2017 19 24979
Fig 1 Resonance
Energy Transfer in real
time Left Non-
adiabatic QUOTE
dynamics
following impulsive
excitation of the energy
donor the adiabatic
potential energy
surfaces are shown for
reference Right
temporal evolution of
the population of the
excited energy acceptor
in a frozen and liquid
polar solvent
I5
Towards an accurate computational photochemistry and photobiology the paradigmatic case of vision
Marco Garavelli1
1 Dipartimento di Chimica Industriale ldquoToso Montanarirdquo Viale del Risorgimento 4 40136 Bologna Italy 2 Affiliazione 2
marcogaravelliuniboit
ABSTRACT
The use of the computer to simulate light induced events in photoactive molecular materials has given access to a detailed description of the molecular motions and mechanisms underlying the reactivity of organic and bio-organic chromophores Thus different computational strategies and tools can now be operated like a ―virtual spectrometer to characterize and understand the photoinduced molecular deformation and reactivity of a given dye allowing for an accurate description of photochemicalphotobiological processes and a rational of the corresponding photophysical properties including time-resolved spectroscopy
This contribution reviews recent advances in this field by presenting methodological developments and applications in modeling the photophysicalphotochemical properties of organic chromophores and complex photoactive molecular architectures Retinal systems and visual proteins will be presented as a paradigmatic case [12] Hybrid QMMM calculations will be shown to be an elective tool for modeling photoinduced events and dynamics including tuningcontrolling effects of the environment For this purpose our new implementation of a general hybrid QMMM approach that is able to integrate some specialized softwares and acts as a flexible computational environment eventually allowing for so far inaccessible calculations (eg non-adiabatic molecular dynamics of unprecedented accuracy on large molecular materials) will be illustrated The information collected by these studies can be exploited for the design of novel photoactive molecular and soft materials including a novel paradigm of electrochromism for applications in a new generation of color tunable displays and e-ink devices Finally our latest achievements in developing (and modeling) non-linear bi-dimensional electronic spectroscopy as a novel diagnostic tool for tracking structuraldynamical problems in complex environments (eg biologically relevant systems such as proteins and DNA) will be presented [34]
REFERENCES
1 D Polli et al Nature 467 (2010) 440 2 B Demoulin et al JPCL 8 (2017) 4407 3 I Rivalta et al PCCP 16 (2014) 16865 4 I Rivalta et al JPCB 118 (2014) 8396
I6
Modellizzazione in fase condensata ad alte pressioni
Gianni Cardini
Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave di Firenze email giannicardiniunifiit
ABSTRACT
La modellizzazione delle proprietagrave strutturali e dinamiche di sistemi in fase condensata dipende essenzialmente dalla corretta descrizione del potenziale di interazione intermolecolare In simulazioni di dinamica molecolare1 si ricorre di solito a modelli di potenziale semi empirici o a metodi ab initio12 nella maggior parte dei casi basati sulla teoria del funzionale della densitagrave (DFT) Nel caso di sistemi sottoposti ad alte pressioni diventa cruciale una corretta descrizione delle interazioni a corto raggio e modelli che consentano eventualmente la rottura e formazione di legami chimici Verranno presentati alcuni risultati di simulazioni di dinamica molecolare ab initio con il metodo Car Parrinello Le simulazioni ab initio su fasi condensate basate su sistemi periodici sono dispendiose e pertanto condotte per tempi brevi e su campioni molto piccoli Inoltre nel campo delle alte pressioni gli sperimentali sono soliti interpretare i dati spettroscopici in termini di proprietagrave di singola molecola e necessitano di una modellizzazione possibilmente veloce per interpretare le loro misure Questo puograve essere ottenuto ricorrendo al metodo XP-PCM proposto da Cammi et al3 che consente di ottenere risultati qualitativi effettuando calcoli in condizioni estreme di pressione su singola molecola
REFERENCES
7 MP Allen amp DJ Tildesley Computer Simulation of Liquids Oxford University Press Oxford UK 2017 8 DMarx and J Hutter Ab Initio Molecular Dynamics Cambridge University Press Cambridge UK 2009 9 R Cammi et al Chem Phys 344 (2008) 135 R Cammi et al J ChemPhys 137 (2012) 154112
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
I4
Solvent dynamics and energy transfer a real time description
Anna Painelli Francesco Di Maiolo
Dipartimento SCVSA Universitagrave di Parma annapainelliuniprit
ABSTRACT
Energy dissipation and relaxation phenomena are crucial to describe the dynamics of excited states The interaction of a molecule with the environment (the bath) is pivotal in this respect bringing theoretical chemistry towards the field of open quantum systems Several strategies are available to quantitatively describe the system-bath interaction most often based on the dynamics of the reduced density matrix Vibrational degrees of freedom must be explicitly described to address internal conversion and the huge dimension of the resulting basis imposes dramatic approximations to the calculation Here we face the problem adopting an essential state model (ESM) description of the molecular systems ESMs proved successful in describing low-energy linear and non-linear optical spectra of several families of organic dyes in terms of a minimal number of electronic states coupled to few effective vibrational modes ESMs successfully account for polar solvation and for intermolecular interactions in molecular aggregates and in energy transfer systems (1 2 3)
Here we present a dynamical non-adiabatic model for Resonance Energy Transfer (RET) Specifically we consider two dyes an energy donor (D) and an energy acceptor (A) Each dye corresponds to a push-pull chromophore described in terms of two electronic states coupled to a single effective vibration Accounting for dissipation phenomena within the Redfield approach we follow the real time dynamics of RET from the excited D towards A (Fig1 left panel) Moreover a newly derived multistate Redfield-Smoluchowski equation is used to investigate how the dynamical disorder induced by polar solvation affects RET (Fig1 right panel)
REFERENCES
1 F Terenziani A Painelli PhysChemChemPhys 17 13074-81 (2015) 2 C Sissa et al Phys Chem Chem Phys 2011 13 12734ndash12744 3 S Sanyal et al PhysChemChemPhys 2017 19 24979
Fig 1 Resonance
Energy Transfer in real
time Left Non-
adiabatic QUOTE
dynamics
following impulsive
excitation of the energy
donor the adiabatic
potential energy
surfaces are shown for
reference Right
temporal evolution of
the population of the
excited energy acceptor
in a frozen and liquid
polar solvent
I5
Towards an accurate computational photochemistry and photobiology the paradigmatic case of vision
Marco Garavelli1
1 Dipartimento di Chimica Industriale ldquoToso Montanarirdquo Viale del Risorgimento 4 40136 Bologna Italy 2 Affiliazione 2
marcogaravelliuniboit
ABSTRACT
The use of the computer to simulate light induced events in photoactive molecular materials has given access to a detailed description of the molecular motions and mechanisms underlying the reactivity of organic and bio-organic chromophores Thus different computational strategies and tools can now be operated like a ―virtual spectrometer to characterize and understand the photoinduced molecular deformation and reactivity of a given dye allowing for an accurate description of photochemicalphotobiological processes and a rational of the corresponding photophysical properties including time-resolved spectroscopy
This contribution reviews recent advances in this field by presenting methodological developments and applications in modeling the photophysicalphotochemical properties of organic chromophores and complex photoactive molecular architectures Retinal systems and visual proteins will be presented as a paradigmatic case [12] Hybrid QMMM calculations will be shown to be an elective tool for modeling photoinduced events and dynamics including tuningcontrolling effects of the environment For this purpose our new implementation of a general hybrid QMMM approach that is able to integrate some specialized softwares and acts as a flexible computational environment eventually allowing for so far inaccessible calculations (eg non-adiabatic molecular dynamics of unprecedented accuracy on large molecular materials) will be illustrated The information collected by these studies can be exploited for the design of novel photoactive molecular and soft materials including a novel paradigm of electrochromism for applications in a new generation of color tunable displays and e-ink devices Finally our latest achievements in developing (and modeling) non-linear bi-dimensional electronic spectroscopy as a novel diagnostic tool for tracking structuraldynamical problems in complex environments (eg biologically relevant systems such as proteins and DNA) will be presented [34]
REFERENCES
1 D Polli et al Nature 467 (2010) 440 2 B Demoulin et al JPCL 8 (2017) 4407 3 I Rivalta et al PCCP 16 (2014) 16865 4 I Rivalta et al JPCB 118 (2014) 8396
I6
Modellizzazione in fase condensata ad alte pressioni
Gianni Cardini
Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave di Firenze email giannicardiniunifiit
ABSTRACT
La modellizzazione delle proprietagrave strutturali e dinamiche di sistemi in fase condensata dipende essenzialmente dalla corretta descrizione del potenziale di interazione intermolecolare In simulazioni di dinamica molecolare1 si ricorre di solito a modelli di potenziale semi empirici o a metodi ab initio12 nella maggior parte dei casi basati sulla teoria del funzionale della densitagrave (DFT) Nel caso di sistemi sottoposti ad alte pressioni diventa cruciale una corretta descrizione delle interazioni a corto raggio e modelli che consentano eventualmente la rottura e formazione di legami chimici Verranno presentati alcuni risultati di simulazioni di dinamica molecolare ab initio con il metodo Car Parrinello Le simulazioni ab initio su fasi condensate basate su sistemi periodici sono dispendiose e pertanto condotte per tempi brevi e su campioni molto piccoli Inoltre nel campo delle alte pressioni gli sperimentali sono soliti interpretare i dati spettroscopici in termini di proprietagrave di singola molecola e necessitano di una modellizzazione possibilmente veloce per interpretare le loro misure Questo puograve essere ottenuto ricorrendo al metodo XP-PCM proposto da Cammi et al3 che consente di ottenere risultati qualitativi effettuando calcoli in condizioni estreme di pressione su singola molecola
REFERENCES
7 MP Allen amp DJ Tildesley Computer Simulation of Liquids Oxford University Press Oxford UK 2017 8 DMarx and J Hutter Ab Initio Molecular Dynamics Cambridge University Press Cambridge UK 2009 9 R Cammi et al Chem Phys 344 (2008) 135 R Cammi et al J ChemPhys 137 (2012) 154112
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
I5
Towards an accurate computational photochemistry and photobiology the paradigmatic case of vision
Marco Garavelli1
1 Dipartimento di Chimica Industriale ldquoToso Montanarirdquo Viale del Risorgimento 4 40136 Bologna Italy 2 Affiliazione 2
marcogaravelliuniboit
ABSTRACT
The use of the computer to simulate light induced events in photoactive molecular materials has given access to a detailed description of the molecular motions and mechanisms underlying the reactivity of organic and bio-organic chromophores Thus different computational strategies and tools can now be operated like a ―virtual spectrometer to characterize and understand the photoinduced molecular deformation and reactivity of a given dye allowing for an accurate description of photochemicalphotobiological processes and a rational of the corresponding photophysical properties including time-resolved spectroscopy
This contribution reviews recent advances in this field by presenting methodological developments and applications in modeling the photophysicalphotochemical properties of organic chromophores and complex photoactive molecular architectures Retinal systems and visual proteins will be presented as a paradigmatic case [12] Hybrid QMMM calculations will be shown to be an elective tool for modeling photoinduced events and dynamics including tuningcontrolling effects of the environment For this purpose our new implementation of a general hybrid QMMM approach that is able to integrate some specialized softwares and acts as a flexible computational environment eventually allowing for so far inaccessible calculations (eg non-adiabatic molecular dynamics of unprecedented accuracy on large molecular materials) will be illustrated The information collected by these studies can be exploited for the design of novel photoactive molecular and soft materials including a novel paradigm of electrochromism for applications in a new generation of color tunable displays and e-ink devices Finally our latest achievements in developing (and modeling) non-linear bi-dimensional electronic spectroscopy as a novel diagnostic tool for tracking structuraldynamical problems in complex environments (eg biologically relevant systems such as proteins and DNA) will be presented [34]
REFERENCES
1 D Polli et al Nature 467 (2010) 440 2 B Demoulin et al JPCL 8 (2017) 4407 3 I Rivalta et al PCCP 16 (2014) 16865 4 I Rivalta et al JPCB 118 (2014) 8396
I6
Modellizzazione in fase condensata ad alte pressioni
Gianni Cardini
Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave di Firenze email giannicardiniunifiit
ABSTRACT
La modellizzazione delle proprietagrave strutturali e dinamiche di sistemi in fase condensata dipende essenzialmente dalla corretta descrizione del potenziale di interazione intermolecolare In simulazioni di dinamica molecolare1 si ricorre di solito a modelli di potenziale semi empirici o a metodi ab initio12 nella maggior parte dei casi basati sulla teoria del funzionale della densitagrave (DFT) Nel caso di sistemi sottoposti ad alte pressioni diventa cruciale una corretta descrizione delle interazioni a corto raggio e modelli che consentano eventualmente la rottura e formazione di legami chimici Verranno presentati alcuni risultati di simulazioni di dinamica molecolare ab initio con il metodo Car Parrinello Le simulazioni ab initio su fasi condensate basate su sistemi periodici sono dispendiose e pertanto condotte per tempi brevi e su campioni molto piccoli Inoltre nel campo delle alte pressioni gli sperimentali sono soliti interpretare i dati spettroscopici in termini di proprietagrave di singola molecola e necessitano di una modellizzazione possibilmente veloce per interpretare le loro misure Questo puograve essere ottenuto ricorrendo al metodo XP-PCM proposto da Cammi et al3 che consente di ottenere risultati qualitativi effettuando calcoli in condizioni estreme di pressione su singola molecola
REFERENCES
7 MP Allen amp DJ Tildesley Computer Simulation of Liquids Oxford University Press Oxford UK 2017 8 DMarx and J Hutter Ab Initio Molecular Dynamics Cambridge University Press Cambridge UK 2009 9 R Cammi et al Chem Phys 344 (2008) 135 R Cammi et al J ChemPhys 137 (2012) 154112
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
I6
Modellizzazione in fase condensata ad alte pressioni
Gianni Cardini
Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave di Firenze email giannicardiniunifiit
ABSTRACT
La modellizzazione delle proprietagrave strutturali e dinamiche di sistemi in fase condensata dipende essenzialmente dalla corretta descrizione del potenziale di interazione intermolecolare In simulazioni di dinamica molecolare1 si ricorre di solito a modelli di potenziale semi empirici o a metodi ab initio12 nella maggior parte dei casi basati sulla teoria del funzionale della densitagrave (DFT) Nel caso di sistemi sottoposti ad alte pressioni diventa cruciale una corretta descrizione delle interazioni a corto raggio e modelli che consentano eventualmente la rottura e formazione di legami chimici Verranno presentati alcuni risultati di simulazioni di dinamica molecolare ab initio con il metodo Car Parrinello Le simulazioni ab initio su fasi condensate basate su sistemi periodici sono dispendiose e pertanto condotte per tempi brevi e su campioni molto piccoli Inoltre nel campo delle alte pressioni gli sperimentali sono soliti interpretare i dati spettroscopici in termini di proprietagrave di singola molecola e necessitano di una modellizzazione possibilmente veloce per interpretare le loro misure Questo puograve essere ottenuto ricorrendo al metodo XP-PCM proposto da Cammi et al3 che consente di ottenere risultati qualitativi effettuando calcoli in condizioni estreme di pressione su singola molecola
REFERENCES
7 MP Allen amp DJ Tildesley Computer Simulation of Liquids Oxford University Press Oxford UK 2017 8 DMarx and J Hutter Ab Initio Molecular Dynamics Cambridge University Press Cambridge UK 2009 9 R Cammi et al Chem Phys 344 (2008) 135 R Cammi et al J ChemPhys 137 (2012) 154112
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
Abstracts dei contributi orali
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O1
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O2
New computational strategies for the calculation of anharmonic force fields
Marco Mendolicchio1 Julien Bloino1 Vicenzo Barone1
1 Scuola Normale Superiore I-56126 Pisa Italy
marcomendolicchiosnsit
ABSTRACT
Spectroscopies such as infrared and Raman are powerful tools for the investigation of the physical-chemical properties of molecular systems providing detailed information related to the structure and dynamics However experimental spectra are tuned by several intertwined effects which can make the interpretation of experimental data very challenging or even unfeasible without the support of reliable computational models [1] From this point of view improvements in the accuracy of calculations can be made by introducing anharmonic effects to the description of nuclear motions In particular the second-order vibrational perturbation theory (VPT2) [2] has been known to offer a good balance between accuracy and computational cost thus permitting the study of medium-to-large systems A prerequisite is the knowledge of the potential energy surface (PES) expanded as a Taylor series in terms of the nuclear coordinates about a reference configuration [3] In practice a semi-diagonal quartic force field is necessary to compute the anharmonic vibrational transition energies
Currently the most common way to obtain third- and fourth-order energy derivatives is through finite differences of analytic second-order derivatives of the PES [45] which have shown their efficiency and reliability for a large range of cases This approach is generally well adapted when the degree of anharmonicity of a given vibration is relatively limited but is not flexible enough to support higher-order derivatives necessary to describe correctly large amplitude motions (LAMs) or when harmonic force constants are not available analytically Hence the standard approach to build the anharmonic PES can become a daunting task and alternative strategies need to be explored In this work a new least-squares fitting approach has been devised and combined with a dynamical sampling scheme where an initial default grid is improved iteratively during the calculation in order to adapt to the shape of the PES
In this contribution the underlying theory and the main features of our computational protocol are presented The procedure described above is not exclusively related to PESs and can be extended to property surfaces This approach has been designed from the outset in order to be completely expandable to properties definable as functions of the nuclear coordinates such as dipole moments and polarizability tensors The convergence of the results can then be monitored for each property separately In this work the sampling used for the semi-diagonal quartic force field has been also used to obtain the set of dipole moment derivatives required for computing anharmonic infrared intensities within the VPT2 framework [5-8] and then the full infrared spectrum
REFERENCES
1 M Biczysko J Bloino and C Puzzarini Wiley Interdiscp Rev Comput Mol Sci 8 (2017) e1349 2 H H Nielsen Rev Mod Phys 23 (1951) 90 3 A G Csaacuteszaacuter Wiley Interdiscp Rev Comput Mol Sci 2 (2012) 273 4 V Barone J Chem Phys 122 (2005) 014108 5 J Bloino A Baiardi M Biczysko Int J Quantum Chem 116 (2016) 1543 6 A Willetts N C Handy W H Green and D Jayatilaka J Chem Phys 94 (1990) 5608 7 J Vaacutezquez and J F Stanton Molecular Physics 104 (2006) 377 8 J Bloino and V Barone J Chem Phys 136 (2012) 124108
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O3
On Optimizing Gaussian Basis sets for Crystalline Solids
Loredana Edith Daga1 Lorenzo Maschio1
1 Diparimento di Chimica Universitagrave di Torino lorenzomaschiounitoit
ABSTRACT
CRYSTAL is a well known ab initio code for solid-state quantum-mechanical simulations one of its peculiar aspects is that it is based on Gaussian type functions1
Although the local nature of the basis allows an accurate description of the electronic distribution in periodic systems allowing for the easy and relatively cheap use of hybrid functionals the calibration-optimization of exponents and coefficients for each atomic species is quite often not straightforward Despite recent attempts2 standardized and well-assessed libraries of basis sets are not available for solids as they are for molecules One reason for that is the wide chemical diversity of different solids where the same atomic species can be present as an ion a covalently bonded atom or involved in a metallic bond
For all of these reasons optimization of a basis set can be system specific and is nowadays often left in the hands of the user In this view we have developed a novel method to optimize the basis sets that we call BDIIS (Basis set Direct Inversion of Iterative Subspace) The method is an application of the well known DIIS algorithm34 to the optimization of basis sets in the spirit of its geometry-optimization variant (GDIIS)5
The DIIS method is today a standard tool in quantum chemistry and provides a significant acceleration of the SCF (self-consistent field) convergence rate The method involves the construction of a suitable error vector at each iteration and its minimization implicates the SCF convergence In a similar manner BDIIS requires the construction of an error vector that in this case instead of being related to SCF parameters is based on previous values of both exponents and coefficients A double-sided numerical derivatives are used as gradients and they are scaled by a suitable scale factor obtained by a line search method We implemented the BDIIS algorithm in the CRYSTAL code1 and in this contribution details of the method and first results will be presented
REFERENCES
1 Roberto Dovesi Alessandro Erba Roberto Orlando Claudio M Zicovich-Wilson
Bartolomeo Civalleri Lorenzo Maschio Michel Reacuterat Silvia Casassa Jacopo Baima Simone Salustro Bernard Kirtman Quantum-mechanical condensed matter simulations with CRYSTAL WIREs Comput Mol Sci 8e1360 2018
2 T Bredow M F Peintinger D V Oliveira Consistent gaussian basis sets of triple-zeta valence with polarization quality for solid-state calculations J Comput Chem 34451-459 2013
3 Maschio L Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator for crystalline solids employing Gaussian basis sets Theoretical Chemistry Accounts 13760 2018
4 P Pulay Convergence acceleration of iterative sequences The case of scf iteration Chem Phys 73393-398 1980
5 P Csaacuteszaacuter and P Pulay Geometry Optimization by Direct Inversion in the Iterative Subspace J Mol Struct Elsevier Science Publisher 11431-34 1984
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O4
Wave function-based approach to probe coherence in ultrafast molecular processes
Emanuele Coccia1 Filippo Troiani2 Stefano Corni12
1 Dipartimento di Scienze Chimiche Universitagrave di Padova via Marzolo 1 Padova Italy 2 Istituto di Nanoscienze CNR via Campi 213A Modena Italy
emanuelecocciaunipdit
ABSTRACT
Revealing possible long-living quantum coherence in ultrafast processes allows detecting genuine quantum mechanical effects in complex systems such as materials and biomolecules [1] To investigate such effects from a quantum chemistry perspective we have developed methods to simulate the time evolution of molecular systems based on ab initio calculations that include the effect of an external medium (eg a solvent plasmonic nanoparticles) on the molecule [2] as well as of dephasing of the electronic wave function The latter has been accomplished by means of the stochastic Schroumldinger equation [3] To test the approach we have simulated [4] femtosecond pulse-shaping ultrafast spectroscopy of terrylenediimide [5] finding that the experimental results could be reproduced Then we have investigated the absorption of light pulses for a more complex system (a molecular chromophore close to a spherical silver nanoparticle) and we found that including dephasing is essential to provide a qualitatively correct picture of metal-enhanced molecular absorption that depends on the interplay of light pulse duration plasmon lifetime and molecular dephasing time [6] Moreover preliminary results on possible plasmon-enhanced high-harmonic generation are shown
REFERENCES
1 G D Scholes et al Nature 543 647 (2017) 2 S Pipolo and S Corni J Phys Chem C 120 28774 (2016) 3 R Biele and R DrsquoAgosta J Phys Condens Matter 24 273201 (2012) 4 E Coccia F Troiani and S Corni J Chem Phys 148 204112 (2018) 5 R Hildner D Brinks and N F van Hulst Nature Phys 7 172 (2011)
6 E Coccia and S Corni in preparation
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O5
Band Shapes of Singlet-Triplet Transitions
Amalia Velardo1 Raffaele Borrelli2 Amedeo Capobianco1 Alessandro Landi1 Andrea Peluso1
1 Dipartimento Chimica e Biologia ldquoAdolfo Zambellirdquo Universitagrave degli Studi di Salerno Via G Paolo II 84084-Fisciano Italy
2 Dipartimento di Scienze Agrarie Forestali e Alimentari Universitagrave degli Studi di Torino Largo Braccini 2 10095-Grugliasco Italy
avelardounisait
ABSTRACT
Triplet states have found a renewed interest because of the important role they play in organic
solid-state optoelectronic devices They are indeed involved in radiative and non radiative
transitions that can significantly affect device efficiency In organic light emitting diodes (OLED)
triplet excitons are preferentially formed over singlet excitons determining to a larger extent the
efficiency of emitted radiation In photovoltaic solar cells triplet states can in principle improve the
efficiency both for the long lifetime of triplet excitons that imply a large diffusion length and for
photon upconversion via triplet-triplet annihilation which provides higher energy photons
However low-lying triplet states could also provide potentially fast charge recombination channels
which can limit the efficiency of energy conversion
Herein we present a full quantum mechanics approach for evaluating from first principles the rates of radiative and radiationless singlet triplet transitions which could be useful for a deeper understanding of the role of triplet states in a solid state device For testing the reliability of the approach we have simulated the spectral band shapes of singlet-triplet transitions of some aromatic compounds used in optoelectronic devices[2] Computed spectral shapes are in excellent agreement with experimental results opening the way for reliable study of non radiative singlet-triplet transitions
REFERENCES
1 A Velardo R Borrelli A Capobianco M V La Rocca and A Peluso J Phys Chem C 119 (2015) 18870-18876 2 A Velardo R Borrelli A Peluso and A Capobianco J Phys Chem C 120 (2016) 24605-24614
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O6
Modeling amide I infrared spectra of proteins insights from a perturbative approach
Laura Zanetti-Polzi1 Massimiliano Aschi1 Andrea Amadei2 Isabella Daidone1
1 Department of Physical and Chemical Sciences University of LAquila Via Vetoio (Coppito1) 67010 LAquila Italy
2 Department of Chemical and Technological Sciences University of Rome ldquoTor Vergatardquo Via della Ricerca Scientifica 00185 Rome Italy laurazanettipolziunivaqit
ABSTRACT
Infrared (IR) absorption spectra of the amide I mode mostly corresponding to the peptide-group C=O stretching have long provided a tool for determining the secondary structure of peptides and proteins Indeed the frequencies of the amide I band are closely correlated to the molecular geometry and hydrogen bonding pattern However the link of particular frequencies with secondary structure has been made on the basis of semiempirical rules and is often controversial Moreover the observed amide I bands are often featureless due to the extensive overlap of the broad underlying component bands Theoreticalminuscomputational methods are needed to provide essential information on the complex relationship between spectroscopic absorption and dynamics permitting the effects of structural transitions and of solvent interactions on the IR signal to be unravelled In this context we proposed and applied an approach to calculate amide I IR spectra of peptides and proteins based on the joint use of extended molecular dynamics (MD) simulations and a mixed quantumclassical theoretical computational methodology the Perturbed Matrix Method (PMM)[1] The use of such an approach allowed the theoretical investigation of the amide I spectra of both helical [23] and β [3-5] peptides as well as amyloids [6] and peptides unfolded states [35] critically comparing the calculated spectra with experimental IR temperature-dependent and isotope-labelled spectra and providing a mean for the interpretation of the experimental spectra at the molecular level More recently we focused on modelling the time-dependence of the amide I IR signal to be compared with experimental time-resolved IR spectra commonly used to monitor folding kinetics [5] The possibility of quantitatively modelling time resolved spectra can provide a detailed interpretation of the time evolution of the spectroscopic signal permitting a full characterization of the kinetics of complex chemical-biochemical processes The investigation of time-dependent IR signals has been applied to the analysis of extremely long (hundreds of microseconds) folding trajectories of two β peptides [7] allowing to reconstruct the IR spectroscopic signal of various conformational states of the peptide and providing a thorough thermodynamic and kinetic picture of the folding process
REFERENCES
1 Amadei A et al Theor Chem Acc 129(1) 31-43 2011 2 Zanetti-Polzi L et al J Phys Chem B 117(41) 12383-12390 2013 3 Zanetti-Polzi L et al J Phys Chem B 116(10) 3353-3360 2012 4 Zanetti-Polzi L et al J Phys Chem B 115(41) 11872-11878 2011 5 Daidone I et al J Phys Chem B 119(14) 4849-4856 2015 6 Zanetti-Polzi L et al J Am Chem Soc 133(30) 11414-11417 2011
7 Zanetti‐ Polzi L et al FEBS Lett 591(20) 3265-32752017
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O7
The effect of distortions of a covalent enzymatic intermediate in Human Transketolase a computational
point of view
Mario Prejanograve1 Tiziana Marino1 Nino Russo 1 Fabiola Medina2 Pedro A Fernandes2 Maria J Ramos2
1 Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende (CS) Italia 2 Departemento de Quimica e Bioquimica Faculdade de Ciencias Universidade do Porto Porto Portugal
emalimarioprejanounicalit
ABSTRACT
Enzymes are biological catalyst that accelerate chemical reactions in time requested by physiological processes and are basically proteins that catalyze highly chemo- stereo- and region-selective reactions
Thanks to that ability from their discovery to nowadays several theories were proposed in order to understand explain and predict behavior of these incredible biological machines
Human Tranketolase is an enzyme belonging to transferase class participates to Pentose Phosphate Pathways and involved in different diseases metabolism like Alzheimerrsquos disease Most recently 1-3 the distortion contribution of a covalent intermediate (out of plane C-C bond C-C bond elongation) has been proposed as fundamental event to the catalysis according with Albery and Knowles theory4
Starting from literature work 3 an accurate computational study has been carried out with the aim of verify confirm and quantify the distortion contribution to the catalytic pathway applying different computational methodologies to different models with different size full ab initio hybrid QMMMONIOM and classical Molecular Dynamics protocols
The Gliceraldheyde-3-phospate formation step was estimated as rate determining step (16 kcalmol-1) according with experimental observations Along the Potential Energy Surface was calculated the effect of distortion observing that highest energy barrier decreases of 16 kcalmol-1
REFERENCES
1P Asztalos C Parthier R Golbik M Kleinschmidt G Hubner M S Weiss R Friedemann
G Wille K Tittmann Biochemistry 46 12037 2007
2L Mitschke C Parthier K Schroeder-Tittmann J Coy K Tittmann J Biol Chem 285
31559 2010 3
S Luumldtke P Neumann K M Erixon F Leeper R Kluger R Ficner K Tittmann Nat
Chem 5 762 2013 4 W J Albery J R Knowles Angew Chem Int Ed Engl 16 285 1977
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O8
La3+
ion in EAN aqueous mixtures a MD-XAS investigation on the effect of water concentration
F Sessa1 V Migliorati1 A Lapi12 P DrsquoAngelo1
1 Department of Chemistry University of Rome ldquoLa Sapienzardquo Rome Italy 2 CNR institute ldquoSezione Meccanismi di Reazionerdquo University of Rome ldquoLa Sapienzardquo Rome Italy
francescosessauniroma1it
ABSTRACT
Ranging from analytical chemistry to electrochemistry Ionic Liquids (ILs) are interesting compounds that have seen a wide array of applications including their use as replacement for organic solvents lubricants reaction and transport media Due to their low volatility and non-flammability as well as their high chemical and thermal stability ILs are safer and more environmental-friendly than the commonly used solvents(1) Since one of IL most interesting application is their use in the nuclear fuel cycle understanding at a molecular level the solvation process of lanthanoid (Ln3+) salts in IL solution is an important piece of information to improve the efficiency of extraction procedures for the separation of lanthanoid metals Taking into account that all ILs are highly hygroscopic it is also important to understand the effect of water on the coordination properties of Ln3+ solvation complexes in IL media
Here we have investigated the effect of water concentration on the structure of La3+ solvation complexes in several aqueous mixtures of ethylammonium nitrate (EAN) which is the most studied protic IL by means of a combination of X-ray absorption spectroscopy (XAS) and molecular dynamics (MD) simulations The MD-XAS approach has been already proven a valuable tool for the study of IL solutions the high selectivity and versatility of the XAS technique allows one to obtain reliable data on liquid samples while MD simulations provide a dynamic atomistic description of the systems(23)
We find that the presence of nitrate anions in the La3+ coordination complexes diminishes as the water content of the mixtures rises Unlike other weakly coordinating anions such as CF3SO3
- or ClO4
-(4) nitrate anions are still found in the coordination complexes at very high water content However nitrate anions do not behave as strongly coordinating anions either(4) as NO3
- does not saturate the coordination complexes unless the water content is very low This suggests that the coordination properties of Ln3+ ions in EAN aqueous mixtures can be suitably tuned by altering the water content of the solvent mixture
REFERENCES
1 M Freemantle An Introduction to Ionic Liquids RSC Publishing 2009 2 A Serva V Migliorati R Spezia P DrsquoAngelo Chem Eur J 23 8424-8433 (2017) 3 F Sessa V Migliorati A Serva A Lapi G Aquilanti G Mancini P DrsquoAngelo Phys Chem Chem Phys 20 2662-2675 (2018) 4 KBinnemans Comprehensive Inorganic Chemistry II Volume 2 Transition Elements Lanthanides and Actinides Elsevier 2013
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O9
Source of Cooperativity in Hydrogen-Bonded Supramolecular Polymers
Diego Cesario12 Stephanie C C van derLubbe1 Pascal Vermeeren1 Francesca Nunzi234 Ceacutelia Fonseca Guerra15
1 Department of Chemistry and Pharmaceutical Sciences and Amsterdam Center for Multiscale Modeling
Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam The Netherlands 2Department of Chemistry Biology and Biotechnology University of Perugia
via Elce di Sotto 8 I-06123 Perugia Italy 3Istituto di Scienze e Tecnologie Molecolari del CNR (ISTM-CNR)
via Elce di Sotto 8 I-06123 Perugia Italy 4Consortium for Computational Molecular and Materials Sciences (CMS)
2
via Elce di Sotto 8 I-06123 Perugia Italy 5Leiden Institute of Chemistry Gorlaeus Laboratories Leiden University
P O Box 9502 2300 RA Leiden The Netherlands E-mail diegocesariostudentiunipgit
ABSTRACT
Cooperative self-assembly expands the possibilities in supramolecular chemistry Hydrogen bonds in long
polymeric chains can experience synergy which is often explained as a manifestation of aromaticity to
enhance hydrogen bonding between the monomers In this work linear chains of urea deltamide and
squaramide have been investigated computationally with dispersion-corrected density functional theory in
the framework of Kohn-Sham molecular orbital theory to shed light on the enhancement in the hydrogen
bonds from a quantum chemical perspective Our Energy Decomposition Analysis (EDA)1 shows that the
sources of the cooperativity are in the electrostatic and orbital contributions for this reason in urea the
same cooperativity is found as in deltamide and squaramide which become respectively a more regular a
triangle and square due to the hydrogen bonding The covalent component in the σ orbital interaction of
the hydrogen bonds plays a crucial role it induces a charge separation in the chains that allows a synergetic
lengthening of the polymers Although geometrical changes suggest an enhancement of the aromaticity
the charge transfer in the electronic system is the real driving force of the enhancement of the hydrogen
bond interactions
REFERENCES
1 Kohn‐ Sham Density Functional Theory Predicting and Understanding Chemistry In Reviews in Computational Chemistry
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O10
Aiming at Color Prediction of Flexible Dyes in Aqueous Solution Combined Molecular Dynamic and Quantum
Mechanic approaches
Gloria Mazzone1 Stefania Di Tommaso1 Alistar Ottochian1 Ilaria Ciofini1 and Carlo Adamo1
1 Chimie ParisTech PSL Research University CNRS Institut de Recherche de Chimie Paris Paris France gloriamazzonechimieparistechpsleu
ABSTRACT
The accurate prediction of spectral features determining the color of dyes in complex environment represent a challenge for industrial research Setting-up a computational protocol allowing to quantitative simulation of the perceived color would provide a cost-effective alternative to the synthesis and characterization of new compounds enabling the design of new dyes with customized properties within shorter time scale
For structurally rigid dyes a theoretical protocol based on a quantum mechanical description in the framework of Time-Dependent Density Functional Theory (TDDFT) in implicit solvent environment allows the prediction of the absorption band shape and position since for such systems the vibronic coupling based on the Frank Condon assumption is expected to be a valid model [1] While the simulation of flexible dyes optical properties requires efficient protocols able to explicitly account for the intrinsic complexity of both solute and solvent Therefore a model that explicitly takes into account the environment embedding the solute has to be considered A procedure based on combination of molecular dynamics and quantum mechanical approaches represent the most promising strategy to reach this aim [2-3]
In this work the spectroscopic properties of various flexible dyes in aqueous solution have been investigated through a theoretical approach combining a classical dynamic sampling of the whole system by using a non-reparametrized force field with TDDFT calculations of the dye under investigation The QM calculations have been performed on representative snapshots chosen as function of the selected degree of freedom taking into account the solvent effects using an implicit model (PCM) and weighing each transition with a Boltzmann distribution to achieve the final spectrum
REFERENCES
1 S Di Tommaso D Bousquet D Moulin F Baltenneck P Riva H David A Fadli J Gomar I Ciofini C Adamo J Comput Chem 2017 38 998
2 N De Mitri S Monti G Prampolini V Barone J Chem Theory Comput 2013 9 4507 3 J Cerezo F J Avila Ferrer G Prampolini F Santoro J Chem Theory Comput 2015 11 5810
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O11
Solid-state effects on the optical excitation of push-pull molecular J-aggregates by first
principles simulations
Michele Guerrini1 Arrigo Calzolari2 and Stefano Corni23
1Dipartimento FIM Universitagrave di Modena e Reggio Emilia Italy
2CNR Nano Istituto Nanoscienze Centro S3 I-41125 Modena Italy
3Dipartimento di Scienze Chimiche Universitagrave di Padova Italy
micheleguerriniunimoreit
ABSTRACT
J-aggregates1 are a class of low-dimensional molecular crystals which display enhanced interaction with
light These systems show interesting optical properties as an intense and narrow red-shifted absorption peak
(J-band)2-5
with respect to the spectrum of the corresponding monomer The need to theoretically investigate
optical excitations in J-aggregates is two-fold a thorough first principles description is still missing and a
renewed interest is raising recently in understanding the nature of the J-band in particular regarding the
collective mechanisms involved in its formation In this work we investigate the electronic and optical
properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull
chromophores6 By using a time-dependent density functional theory approach we assess the role of the
molecular packing in the enhancement and red-shift of the J-band along with the effects of confinement in
the optical absorption when moving from bulk to low-dimensional crystal structures We simulate the
optical absorption of different configurations (ie monomer dimers a polymer chain and a monolayer sheet)
extracted from the bulk crystal By analyzing the induced charge density associated to the J-band we
conclude that it is a longitudinal excitation delocalized along parallel linear chains and that its overall red-
shift results from competing coupling mechanisms some giving red shift and others giving blue shift which
derive from both coupling between transition densities and renormalization of the single particle energy
levels
REFERENCES
1 Jelley E E Spectral Absorption and Fluorescence of Dyes in the Molecular State Nature 1936 138 1009-1010
2 Wuumlrthner F Kaiser T E Saha-Moumlller C R J-aggregates from serendipitous discovery to supramolecular
engineering of functional dye materials Angew Chem Int Ed 2011 50 3376-3410
3 Egorov V V Alfimov M V Theory of the J-band From the Frenkel exciton to charge transfer Phys -Usp 2007 50
985
4 Eisfeld A Briggs J S The J-band of organic dyes lineshape and coherence length Chem Phys 2002 281 61-70
5 Eisfeld A Briggs J S The J- and H-bands of organic dye aggregates Chem Phys 2006 324 376-384
6 Botta C Cariati E Cavallo G Dichiarante V Forni A Metrangolo P Pilati T Resnati G Righetto S Terraneo
G Tordin E J Mater Chem C 2014 2 5275-5279
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O12
Previsione dei Tempi di Rilassamento NMR di Molecole Flessibili Oligosaccaridi come Caso di Studio
Mirco Zerbetto1 Antonino Polimeno1 Goumlran Widmalm2
1 Dipartimento di Scienze Chimiche Universitagrave degli Studi di Padova Padova 35313 Italia 2 Department of Organic Chemistry Stockholm University S-106 91 Stockholm Sweden
mircozerbettounipdit
ABSTRACT
Le misure di rilassamento di risonanza magnetica nucleare (NMR) di molecole in cui uno o piugrave atomi vengono arricchiti isotopicamente (ad es 2H 13C 15N 17O) non solo sono in grado di fornire informazioni strutturali di una molecola (dai gruppi funzionali presenti alla struttura 3D in soluzione) ma sono anche sensibili alla dinamica molecolare a tempi lunghi
LrsquoNMR egrave particolarmente diffusa nello studio della dinamica di molecole biologiche [1] sistemi che possono presentare un elevato grado di flessibilitagrave (si pensi ad esempio alle proteine intrinsecamente disordinate) La dinamica influenza perograve in maniera indiretta e complessa i dati sperimentali quali i tempi di rilassamento spin-spin e spin-reticolo per cui sono necessari modelli interpretativi della dinamica molecolare e in particolare delle dinamiche lente Se da una parte il confronto tra il dato sperimentale e il modello teorico puograve essere usato per estrapolare informazioni di natura molecolare da misure di rilassamento NMR lrsquoottica che spinge il progetto qui presentato egrave invece quella della previsione del comportamento a tempi lunghi di sistemi complessi attraverso la messa a punto di un protocollo multiscala per la simulazione ―ab initio di misure di rilassamento NMR che passa attraverso una scelta euristica delle coordinate rilevanti la definizione di una equazione di Smoluchowski per la dinamica stocastica di tali coordinate e lrsquoutilizzo di dinamiche molecolari Browniane per la propagazione della dinamica e il calcolo delle osservabili spettroscopiche [2]
Piccoli oligosaccaridi composti da 2-5 unitagrave zuccherine sono stati finora impiegati allo scopo di mettere a punto tale metodologia multiscala I carboidrati a differenza di altre molecole biologiche (proteine DNA) presentano diversi schemi di legame e possibilitagrave di ramificazione Per questo motivo sono un ottimo caso di studio percheacute richiedono lo sviluppo di modelli per la dinamica che siano sensibili a differenze anche molto localizzate a livello molecolare ma che possono condurre a proprietagrave anche molto diverse su scala temporale ampia Inoltre recentemente i carboidrati hanno attirato un elevato interesse tecnologico soprattutto le nanocellulose [3] Usando come leitmotiv gli oligosaccaridi si discuteragrave lrsquoapproccio sviluppato anche in termini della sua applicabilitagrave a sistemi piugrave complessi
REFERENCES
1 Sheppard D Spranger R Tugarinov V NMR Spettrosc 2010 56 1 2 Zerbetto M Polimeno A Int J Quantum Chem 2016 116 1706 3 Moon R J Martini A Nairn J Simonsen J Youngblood J Chem Soc Rev 2011 40 3941
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O13
Self interaction charge delocalization electrolyte ionization
F Faglioni1 WA Goddard III2 B Merinov2 E Fadel3 G Samsonidze3 N Molinari3 J Grossman3 J Mailoa3 B Kozinsky4
1 DSCG Univ of Modena and Reggio Emilia Modena Italy
2 MSSC California Institute of Technology Pasadena (CA) USA
3 Robert Bosh Research and Technology Center Boston (MA) USA
4 Paulson School of Engineering amp Appl Sciences Harvard University Boston (MA) USA
francescofaglioniunimoreit
ABSTRACT
We investigate the effect of charge delocalization associated to a lack of self interaction correction in many popular density functionals and its effect on the description of the decomposition pathway for several lithium battery electrolytes as observed during electrochemical cycling1 This effect has been known for decades2 and although is usually neglected for reactions involving closed shell systems or single uncharged radicals we show that it plays a fundamental role for anion ionization in solution where its inclusion changes the qualitative description of the ionization process and the subsequent decomposition pathway
After sceening a number of DFT methods we investigated four anions (TFSI(-) PF6(-) DTI(-) BF4(-)) and four solvents (DMSO DME PC AN) as potential components for next generation lithium-metal rechargeable batteries3
We provide a simple electrostatic model to explain the predicted behavior This model will guide electrochemists in the design of stable electrolytes and to determine recharging conditions to prevent or reduce cell failure
1 Nakyama M et al Energy Environ Sci 3 1995 (2010) 2 Johnson BG et al Chem Phys Lett 221 100 (1994) 3 E Fadel et al in preparation
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O14
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O15
Simulations of a liposomal assisted delivery of the Temoporfin photosensitizer
Martina De Vetta12 Omar Baig1 Juan J Nogueira1 Leticia Gonzaacutelez1
1 Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna Waumlhringer Str 17 A-1090 Vienna Austria
2 Departamento de Quiacutemica Universidad Aut noma de Madrid Francisco Tomaacutes y Valiente 7 28049 Cantoblanco Madrid Spain
martinadevettaunivieacat
ABSTRACT
Assisted delivery formulations of photosensitizers employed in photodynamic therapy are currently applied or under development to solve the problems created by the hydrophobic nature of many of these compounds Liposomes are particularly suitable carriers thanks to the hydrophobicity of the inner double layer and the hydrophilic character of the outer surface The efficacy of such assisted delivery formulations is bounded to the inter-molecular interactions between the drug and the carrier material1 To provide insight on the nature of such interactions we have employed all-atom molecular dynamics to simulate the liposomal formulation of Temoporfin a porphyrin-based photosensitizer Atomistic resolution despite costly for such macromolecular assembly was essential to identify the origin of the exceptional loading capacity and the rigidity of the nano-carrier in the presence of the drug Temoporfin is found to be a rather good hydrogen donor and forms an extended hydrogen bond network with the polar heads of the phospholipids such short range and directional interactions modify the diffusion of the lipid molecules and assure the stability of the drug-liposome complex2 These intermolecular interactions are also expected to influence the delivery of the drug from the carrier to the targeted cells through the cellular membrane This process has been investigated with umbrella-sampling molecular dynamics Then the influence of the membrane hydrophobic environment on Temoporfin electronically excited states was also investigated In particular we have computed the UV-vis absorption spectrum and the lower tripletsrsquo density of states by an electrostatic-embedding QMMM scheme considering an ensemble of geometries at the minimum of the free-energy profile from the umbrella sampling simulation Such calculations have also been performed in methanol for which in addition different theoretical models and sampling techniques have been employed and compared to the experimental absorption spectrum measured in methanol
REFERENCES
1 A S L Derycke P A M De Witte Adv Drug Deliv Rev 2004 56 17ndash30 2 M De Vetta L Gonzaacutelez J J Nogueira ChemistryOpen (accepted) 2018
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O16
The best of both worlds combining Markov State Models and Path Collective Variables to describe
protein-ligand binding
Matteo Masetti1
1 Department of Pharmacy and Biotechnology (FaBiT) Alma Mater Studiorum ndash University of Bologna Italy matteomasetti4uniboit
ABSTRACT
A reliable estimation of binding affinities and binding rates is of paramount importance for computational drug discovery[1] Thanks to recent advances in hardware and sampling methodologies Molecular Dynamics (MD) simulations are becoming increasingly effective and they are emerging as a valid alternative to molecular docking (dynamic docking)[2] Typically two classes of orthogonal approaches based on MD frameworks can be envisioned Unbiased (or brute force) MD simulations followed by Markov State Models (MSM) analysis are gaining increasing popularity as they have the advantage of providing a comprehensive kinetic (and thermodynamic) picture of the process under investigation[3] Unfortunately unless unconventional computational resources are available the CPUGPU-intensive nature of this approach does not comply with an accurate characterization of rate constants[4] On the other hand biased-MD approaches like metadynamics[5] have proven to be effective in determining free energy profiles of complex events as long as suitable reaction coordinates (or collective variables CVs) are provided Among these Path Collective Variables (PCVs) represent an optimal choice to describe protein-ligand association but their effectiveness relies on a prior knowledge of the mechanism one wishes to characterize[6]
Here we present a combined approach suited to fully characterize the energetics of protein-ligand binding making optimal use of computational resources We apply the methodology to a pharmaceutically relevant problem like the association of Alprenolol to the β-adrenergic receptor for which a set of previously computed trajectories were made available[7] In particular the Markov states are firstly identified and then employed to feed PCVs Thus the free energy profile of Alprenolol binding is reconstructed via well-tempered metadynamics[8] The reliability of calculations is finally assessed through statistical analysis approaches
REFERENCES
1 Pan AC Borhani DW Dror RO Shaw DE Molecular determinants of drugndashreceptor binding kinetics Drug Discov Today 2013 18
2 Gioia D Bertazzo M Recanatini M Masetti M Cavalli A Dynamic docking a paradigm shift in computational drug discovery Molecules 2017 22
3 Husic BE Pande V Markov state models from an art to a science J Am Chem Soc 2018 140 4 De Vivo M Masetti M Bottegoni G Cavalli A Role of molecular dynamics and related methods in drug discovery J Med Chem
2016 59 5 Laio A Parrinello M Escaping free-energy minima Proc Natl Acad Sci USA 2002 99 6 Branduardi D Gervasio FL Parrinello M From A to B in free energy space J Chem Phys 2007 126 7 Dror RO Pan AC Arlow DH Borhani DW Maragakis P Shan Y Xu H Shaw DE Pathway and mechanism of drug
binding to G-protein-coupled receptors Proc Natl Acad Sci USA 2011 108 8 Barducci A Bussi G Parrinello M Well-tempered metadynamics a smoothly converging and tunable free-energy method Phys
Rev Lett 2008 100
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O17
The mechanism of post-translation regulation of estrogen biosynthesis in Breast cancer cells as revealed by atomic level multiscale simulations
Ida Ritacco1 Angelo Spinello1 Alessandra Magistrato1
1 CNR-IOM co SISSA via Bonomea 265 34136 Trieste Italy
HYPERLINK mailtoiritaccosissait
ABSTRACT
Human Aromatase (HA) is a heme-protein belonging to the cytochrome P450 family This
catalyzes the conversion of androgens to estrogens through reactions requiring oxygen and
electrons provided by NADPH cytochrome reductase (CPR)1 However high levels of estrogens
resulting from enhanced HA activity are related to abnormal cellular proliferation which leads to
several diseases among which breast cancer (BC) Recently it has been shown that post-
translational regulation of HA by the tyrosine 361 (Y361) phosphorylation up-regulates HA activity2
It is hypothesized that phosphorylated Y361 accelerates the electronic transfer (ET) from the CPR
to the heme of the HA enhancing estrogen biosynthesis Aim of this work was to rationalize both
the mechanism of post-translation regulation and the interaction mechanism of HA with CPR
combining different computational techniques eg protein-protein docking molecular dynamics
(MD) simulations and hybrid quantum-classical (QMMM) MD simulations These simulations
unprededently reveal that phosphorylation only slightly affects the ET rate between the FMN
domain of the CPR and HA while having the largest impact on the stabilization of the CPRHA
adduct
REFERENCES
1 1 Y Dai et al Steroids 2015 101 116-124 2 2 S Catalano et al Mini Rev Med Chem 2016 16(9) 691-698
HA
FMN domain of CPR
eoline
androgens
estrogens
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O18
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O19
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O20
Tuning Proximal and Remote Steric Effects in the Rationalization of Catalytic Behavior
Laura Falivene and Luigi Cavallo
KAUST Catalysis Center King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
Email HYPERLINK mailtolaurafalivenekaustedusa
ABSTRACT
Rationalizing the behavior of transition metal catalysts often consists in relating their performance
to the steric and electronic properties of the ligand As for steric effects the classical Tolman cone
angle θ developed for phosphane type ligands certainly is among the most famous1 However this
descriptor is biased towards phosphanes which makes it less useful when different type of ligands
have to be analyzed In this scenario we developed another descriptor the percent of buried
volume VBur23 which has been used to correlate catalytic behavior to the structure of the catalyst
using typical structure-property relationships4
As typical for numerical descriptors the VBur only captures average properties of a given ligand
missing completely the way space occupation around the metal center occurs To overcome this
limitation we introduced topographic steric maps as a natural evolution of the VBur35 Steric maps
allow having a clear image of the surface of interaction between the transition metal based catalyst
and the substrate Nonetheless extracting numbers from steric maps to be used in multivariate
linear correlations aimed at rationalizing experimental behavior is not straightforward To this end
we developed a buried volume approach aimed at separating the coordination space around the
metal into proximal and remote zones In this contribution we will show how tuning the separation
between proximal and remote zones and how this separation allows to achieve good
rationalization of catalytic behavior in a series of test cases
REFERENCES
1 C A Tolman Chem Rev 1977 77 313-348 2 A Poater B Cosenza A Correa S Giudice F Ragone V Scarano L Cavallo Eur J Inorg Chem 2009 1759-1766 3 L Falivene R Credendino A Poater A Petta L Serra R Oliva V Scarano L Cavallo Organometallics 2016 35 2286-92 4 L Falivene L Cavallo G Talarico ACS Catal 2015 5 6815-21 5 F Ragone A Poater L Cavallo J Am Chem Soc 2010 132 4249-4258
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O21
Investigating photoelectrochemical properties of dye-electrode interfaces with density functional embedding
theory
E Schiavo1 A B Muntildeoz-Garciacutea2 F Libisch3 and M Pavone1
1 Department of Chemical Sciences University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
2 Department of Physics University of Naples Federico II Comp Univ Monte SantrsquoAngelo Via Cintia 21 80126 Naples Italy
3 Institute for Theoretical Physics Vienna University of Technology Wiedner Hauptstraszlige 8 Vienna eduardoschiavouninait
ABSTRACT
Dye-Sensitized Solar Cells (DSSCs) are complex photoelectrochemical devices where the interfaces between different components play a crucial role for the overall performance1 From the theoretical point of view the study of such interfaces presents many challenges for state of the art computational tools In particular the modelling of the photochemistry involving molecular dyes requires high levels of theory that are able to accurately treat excited states The standard computational approach for extended solid-state systems is Density Functional Theory (DFT) which by construction is only capable of treating ground state properties Conversely the realistic modelling of the electrode nanoparticles covered by anchored dyes requires a model system size that cannot be handled by accurate methods eg GW or correlated wavefunction approaches
In this contribution we propose to solve this problem by means of density functional- embedding theory (DFET)2-3 Briefly embedding methods allow partitioning of a system in two subsets the cluster and the environment The total energy is the sum of those from the two subsets plus an interaction term This partition allows us to treat the cluster with accurate and demanding methods while retaining the effects of the environment at the DFT level DFET defines a unique embedding potential mediating the interaction between the cluster and the environment The potential is obtained by a modified optimized effective potential method4 under the constraint that the sum of the densities of the subsets matches the density of the total system
In the past few years many works have been published on the development implementation and testing of different embedding schemes56 Most of these works focus on the performance of embedding methods when applied to benchmark systems Here we apply DFET for a real p-type DSSC interface model a Coumarin-based dye (C343) adsorbed on p-type NiO which is the current standard for DSSC photocathodes7 We test DFET by characterizing the electronic structure of the dye with methods beyond DFT while treating the NiO environment with DFT(+U) Our results assess the importance of having a proper embedding potential to obtain accurate results for the photochemical properties of adsorbed dyes in p-type DSSCs
REFERENCES
1 A Hagfeldt G Boschloo L Sun L Kloo and H Pettersson Chem Rev 110 (2010) 6595 2 C Huang M Pavone and E A Carter J Chem Phys 134 (2011) 154110 3 K Yu F Libisch and E A Carter J Chem Phys 143 (2015) 102806 4 Q Wu and W Yang J Chem Phys 118 (2003) 2494 5 S Prager A Zech F Aquilante A Dreuw T A Wesolowski J Chem Phys 144 (2016) 204103 6 F R Manby M Stella J D Goodpaster T F Miller III J Chme Theory Comput 8 (2012) 2564 7 A B Muntildeoz-Garciacutea and M Pavone Phys Chem Chem Phys 17 (2015) 12238
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
O22
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
Abstracts dei poster
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P1
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P2
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P3
Core-Electron Excitations in Dibenzothiophene Derivatives A Joint Experimental and Theoretical
NEXAFS and XPS Investigation
E Bernes1 D Toffoli1 M Stener1 G Fronzoni1 M de Simone2 M Coreno3 C Grazioli3 A Guarnaccio3 A Santagata3 C Puglia4 and T Zhang4
1Department of Chemical and Pharmaceutical Sciences University of Trieste 34127 Trieste Italy
2IOM-CNR Laboratorio TASC Sincrotrone Trieste I-34149 Trieste Basovizza Italy
3ISM-CNR Potenza and Trieste LD2 Unit Italy
4Department of Physics and Astronomy
Uppsala University Box 516 SE-751 20 Uppsala Sweden
email HYPERLINK mailtoELISABERNESstudentiunitsit
ABSTRACT
Derivatives of dibenzothiophene (DBT) subsituted with diphenylphosphine oxide find promising application in the development of organic light-emitting diodes (OLEDs1) Due to their potential in the development organic devices a detailed investigation of their electronic properties is of fundamental importance In this respect core electron spectroscopies such as Near-Edge X-ray Absorption Fine-Structure (NEXAFS2) and X-ray photoelectron spectroscopy (XPS) are useful tools to investigate the electronic structure of molecules of varying complexity due to the localized nature of the initial excited state Density functional theory (DFT) calculations at the Kohn-Sham and time-dependent DFT of the 28-Bis(diphenylphosphoryl)dibenzo[bd]thiophene (PPT) and of its constituents building blocks were carried out to simulate measured XPS and NEXAFS spectra at the CO K-edges and S P LII ed LIII edges with the aim of obtaining an extensive comprehension of their electronic structure The XPS and NEXAFS measurements were performed at the Gas Phase Photoemission beam line of the Elettra synchrotron in Trieste3 C and O K-edge spectra were simulated at the DFT level by using the transition potential method while S and P LII ed LIII edges were calculated at the TDDFT level within the ZORA approximation4 The very good agreement between theory and experimental data permits an unambiguous assignment of the spectra and provides a detailed picture of the electronic structure of this important class of systems
REFERENCES
1 S H Jeong and J Y Lee J Mater Chem 21 (2011) 14604-14609 D Kim S Salman V Coropceanu E Salomon A B Padmaperuma L S Sapochak A Kahn and J-L Bredas J Chem Mater 22 (2010) 247-254
2 J Stoumlhr NEXAFS Spectroscopy Springer-Verlag 1992
3 K C Prince R R Blyth R Delaunay M Zitnik J Krempasky J Slezak R Camilloni L Avaldi M Coreno G Stefani C Furlani M de Simone S Stranges J Sync Rad 5 (1998) 565 4 F Wang T Ziegler E van Lenthe S van Gisberger and E J Baerends J Chem Phys 122 (2005) 204103
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P4
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P5
Seeking new materials for singlet fission covalent dimers as an alternative to molecular crystals
Davide Accomasso Giovanni Granucci Maria Bruna Stella Maurizio Persico
Department of Chemistry and Industrial Chemistry University of Pisa Italy HYPERLINK mailtodavideaccomassodcciunipiit
ABSTRACT
Singlet fission is a process in which a chromophore A in an excited singlet state (S1) transfers part of its excitation energy to a neighbouring chromophore B in the ground state (S0) and both are
converted into triplet excited states (T1)1 2
A(S1) + B(S0) rarr A(T1) + B(T1) The process represents an opportunity to improve the solar energy conversion efficiency in photovoltaic devices In fact a sensitizer capable of quantitative singlet fission may generate two charge carrier pairs per absorbed photon in a semiconductor material The efficiency of singlet fission depends on the interaction between the two chromophores which in turn is highly sensitive to their relative orientation The difficulty in engineering molecular crystals with favourable interchromophore electronic coupling motivated the idea of intramolecular singlet fission ie to have the process occur within a molecule consisting of two covalently linked chromophore units In covalent dimers the geometry and strength of interchromophore coupling can be tuned through chemical synthesis with an high degree of control difficult to achieve in crystals of monomers Moreover for applications of singlet fission in photovoltaics covalent dimers offer potential practical implementations in fact they can be adsorbed on the surface of a semiconductor material as individual units We propose here a computational protocol to design new covalent dimers for singlet fission and to test their suitability The procedure includes the following steps (i) search for new candidate singlet fission chromophores by designing small molecules and computing the excitation energies for their low-lying electronic states (ii) identification of the most favorable dimeric geometries for singlet fission by evaluating the electronic coupling between the initial cmiddot(S1S0) + cmiddot(S0S1) and final 1(T1T1) state of the process (iii) selection of a way to covalently connect two molecules of the candidate chromophore so as to tune their relative orientation (iv) simulation of the excited state dynamics for the covalent dimer first in vacuum and then adsorbed on a semiconductor material
using a trajectory surface hopping approach3
The excited state dynamics simulation is particularly important not only to determine the singlet fission quantum yield but also to identify competing processes and other deficiencies of the
selected chromophore4
REFERENCES 1 M B Smith and J Michl Singlet fission Chem Rev 1106891ndash6936 2010 2 M B Smith and J Michl Recent advances in singlet fission Annu Rev Phys Chem 64361ndash386 2013
3 G Granucci M Persico and A Toniolo Direct semiclassical simulation of photochemical processes with semiempirical wave functions J Chem Phys 114(24)10608ndash10615 2001
4 D Accomasso G Granucci R W A Havenith M Persico Testing new chromophores for singlet fission a computational protocol applied to 23-diamino-14-benzoquinone Chem Phys Submitted
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P6
Proton transfer mechanisms in protic ionic liquids
Henry Adenusi1 Enrico Bodo1
1 Chemistry Department University of Rome ldquoLa Sapienzardquo Italy HYPERLINK mailtohenryadenusiuniroma1it
ABSTRACT
In the emerging field of ionic liquids (ILs) a class of compounds known as protic ionic liquids (PILs)
have received increased interest due to their physicochemical properties A key benefit of PILs
stems from their anhydrous proton conductivity PILs are generally synthesized using equimolar
amounts of a Broumlnsted acid and a Broumlnsted base Proton transfer from the acid to the base forms
proton donor and acceptor sites leading to the formation of hydrogen bond networks This class of
ILs possess low vapour pressure low flammability high thermal and electrochemical stability 1 It is
these properties which make them ideal candidates for use in electrochemical applications Further
investigation of the ionic transport behaviour of PILs is essential for the design of electrochemical
devices with improved performance and safety 2
Currently it is not fully understood how molecular modifications contribute to macroscopic proton
diffusion nor how this impacts the bulk electrical properties of the PIL In this study cationic and
anionic moieties are under investigation to understand proton transfer mechanisms in PILs
Candidate PIL structures for superionic proton diffusion have been generated by the addition of
amphoteric substituents on the side chains of typical aprotic ionic liquids (AILs) These side chains
equipped with a protic function should facilitate proton diffusion potentially in a Grotthuss type
mechanism
Recent studies within our group 3 4 have shown specific substituents on anionic moieties in PILs
can develop complex patterns of hydrogen bond interactions Proton transfer via intra and
intermolecular processes have been observed in amino acid ILs
Figure 1 Candidate cation (imidazolium based) and anion (dicyanamide) which have displayed
proton exchange between cation-anion and cation-cation
Imidazolium cations (Figure 1) represent one of the major cationic counterparts used in PILs thus
they have been modified to allow the formation of hydrogen bonding networks to enable high
conductivity mechanisms
REFERENCES
1 Scott T Handy Ionic liquids classes and properties Intech 2011 2 Hiroyuki Ohno Electrochemical aspects of ionic liquids Wiley 2005 3 Andrea Le Donne and Enrico Bodo Journal of Molecular Liquids 249 2018 1075ndash1082 4 M Campetella M Montagna L Gontrani E Scarpellini and E Bodo Physical Chemistry Chemical Physics 2017 19 11869
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P7
CRYSPLOT a new tool to visualize physical and chemical properties of crystalline solids
Giorgia Beata12 Gianpaolo Perego2 Bartolomeo Civalleri 1
1 Dipartimento di Chimica Universitagrave di Torino Via Giuria 7 I-10125 Torino Italy 2 Aethia Srl Via Ribes 5 10010 Colleretto Giacosa (TO) Italy
giorgiabeataaethiacom
ABSTRACT
Visualization tools are becoming more and more important to analyze help in understanding and present scientific data [1] Here we present a new visualization tool dubbed as CRYSPLOT [2]
Fig 1 Screenshot of the CRYSPLOT web page Fig 2 Example of a combine band structure and DOSs plot
CRYSPLOT is an online web-oriented tool ( HYPERLINK httpcrysplotcrystalsolutionseu
Fig 1) to visualize computed properties of periodic systems It is targeted for plotting properties of crystalline solids as computed with the CRYSTAL code [34] In particular the list of available properties to be plotted is band structure and density of states (DOSs) (see Fig 2) crystal orbital overlap population and crystal orbital Hamiltonian population electron charge density maps profiles and differences electrostatic potential maps Compton profiles and autocorrelation function Simulated infrared Raman and reflectance spectra phonon band structure and density of states Baderrsquos topological analysis functions (eg electron density Laplacian hellip) Transport properties as electron conductivity Seebeck coefficient and electron thermal conductivity Along with plotting CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics
CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries namely Plotly [5] The programming language used for CRYSPLOT is Javascript Our code parses the input files checks if the uploaded files are correct and if they are it reads the data and organizes them into objects ready to be plotted with plotlyjs library It is modular and flexible so that it is very simple to add other input data formats
Overall CRYSPLOT is a modern and flexible online tool that makes CRYSTAL more users friendly It is totally free easy to use and accessible to users from all over the world through its web page [2]
REFERENCES
1 M Valle ―Visualization A Cognition Amplifier Int J Quant Chem 113 (2013) 2040ndash2052 2 G Beata G Perego B Civalleri in preparation Web page HYPERLINK httpcrysplotcrystalsolutionseu 3 R Dovesi A Erba R Orlando C M Zicovich-Wilson B Civalleri L Maschio M Rerat S Casassa J Baima S Salustro B
Kirtman ―Quantum‐Mechanical Condensed Matter Simulations with CRYSTAL WIREs Comput Mol Sci e1360 (2018) 4 R Dovesi V R Saunders C Roetti R Orlando C M Zicovich-Wilson F Pascale B Civalleri K Doll N M Harrison I J Bush P
DrsquoArco M Llunell M Causagrave Y Noeumll L Maschio A Erba M Rerat S Casassa ―CRYSTAL17 Users Manual (University of Torino Torino 2017)
5 Plotly Technologies Inc Collaborative data science Montreacuteal QC 2015 httpsplotly
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P8
Molecular dynamics simulations of zinc proteins a new force field
Marco Pagliai1 Marina Macchiagodena1 Claudia Andreini12 Piero Procacci1 Gianni Cardini1
1 Dipartimento di Chimica ldquoUgo Schiffrdquo Universitagrave degli Studi di Firenze via della Lastruccia 3 50019 Sesto Fiorentino (FI) Italy
2 Centro di Ricerca di Risonanze Magnetiche Universitagrave degli Studi di Firenze via L Sacconi 6 50019 Sesto Fiorentino (FI) Italy
marcopagliaiunifiit
ABSTRACT
Zinc is one of the most abundant metal ions in proteins Zinc binding sites can be described through 3D models called Minimal Functional Sites (MFSs) composed of the metal ion(s) the ligands and all those residues that fall within 5 Aring from at least one metal ligand and can thus influence the metal properties and function [1] It has been shown that zinc MFSs can be grouped into 10 clusters which share a similar local structural arrangement
Classical molecular dynamics simulations are one of the computational methods usually applied to study structural and dynamic properties of metalloproteins [2] The reliability of the simulations is related to the accuracy of the force field (FF) in describing the metalprotein interactions
A new computational procedure has been developed to optimize a series of FF parameters for metalloproteins This procedure relies on ab initio calculations in the framework of density functional theory (DFT) which have been carried out with the CP2K suite of programs [3] Molecular dynamics simulations with a new FF have been performed on a series of C2H2-type zinc finger proteins providing results in agreement with experiments
REFERENCES
1 C Andreini I Bertini G Cavallaro PLoS One 6 2011 e26325 2 L Banci Curr Opin Chem Biol 7 2003 143-149 3 J Hutter M Iannuzzi F Schiffman J VandeVondele WIREs Comput Mol Sci 4 2014 15-25
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P9
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P10
Unveiling the role of structural features in Na insertion mechanism at anatase surfaces new insights for Na-ion
batteries development
Arianna Massaro1 Ana B Muntildeoz-Garcigravea2 and Michele Pavone1
1 Department of Chemical Science University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples Italy 2 Department of Physics ldquoEttore Pancinirdquo University of Naples ldquoFederico IIrdquo via Cintia 21 80126 Naples
Italy HYPERLINK mailtoariannamassarouninait
ABSTRACT
Na-ion batteries (NIBs) are attracting widespread interest as a potentially more convenient alternative to current state-of-the-art Li-ion batteries (LIBs) for large-scale grid energy storage applications [1 2] Despite similar working principles different component materials especially negative electrodes that can accommodate the larger sodium ions must be employed in NIBs [3 4] Recently TiO2 emerged as a promising negative electrode material in both LIBs and NIBs thanks to its inherent safety structural stability and low cost [5 6] Morphological features of TiO2 seem to be crucial and so the fine tuning of crystal phases exposed surfaces nanostructures size and shape is one of the most exploited research heading in this field The tuning of the nanostructures shape can be driven toward the exposition of selected surfaces Thus it is essential to understand how sodium atoms interact and migrate into the lattice in order to address the synthesis toward the highest-efficiency nanomaterial
To this end we propose a theoretical investigation of the Na-insertion mechanism through three different TiO2 surfaces We investigate the Na-insertion process through (101) (100) and (001) surfaces of TiO2 anatase by means of first-principles calculations We show that (001) surface is more active toward Na-insertion showing the lowest migration barrier due to the structural features of the lattice We also model the process upon second Na-insertion in order to give predictions on the long-term stability of each exposed surface
REFERENCES
1 Scrosati B Garche J Lithium batteries Status prospectus and future J Power Sources 2010 195 2419-30 2 Larcher D Tarascon JM Towards greener and more sustainable batteries for electrical energy storage Nature Chem 2015 7 19-29 3 Wang LP Yu L Wang X Srinivasan M Xu ZJ Recent developments in electrode materials for sodium-ion batteries J Mater Chem
A 2015 3 9353-78 4 Dai Z Mani U Teng Tan H Yan Q Advanced Cathode Materials for Sodium-Ion Batteries What Determines Our Choices Small
Methods 2017 1 1700098-124 5 Bella F Muntildeoz-Garcigravea AB Meligrana G Lamberti A Destro M Pavone M Gerbaldi C Unveiling the controversial mechanism of
reversible Na storage in TiO2 nanotube arrays Amorphous versus anatase TiO2 Nano Res 2017 10(8) 2891-903 6 Longoni G Pena Cabrera RL Polizzi S DrsquoArienzo M Mari CM Cui Y Ruffo R Shape-Controlled TiO2 Nanocrystals for Na-ion
Battery Electrodes The Role of Different Exposed Crystal Facets on the Electrochemical Properties Nano Lett 2017 17 992-1000
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P11
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
De novo protein design represents an attractive challenge in which both structure and function are built from scratch Indeed these enzyme-like catalysts could play a pivotal role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] At this purpose the catalytic mechanism of the engineered Cys-His-Glu triads was explored by means of Molecular Dynamic simulation (MDs) molecular recognition and hybrid QMMM approaches Starting from the X-ray crystallographic coordinates of the apo-form of the heptameric coiled coil deposited in the Protein Data Bank (PDB5EZC) [4] we submitted 100 ns of MDs by using AMBER16 [5] Based on the structural knowledge molecular docking of the p-nitrophenyl acetate (pNPA) to de novo proteins was carried out by using AutoDock42 [6] and 10 poses for ligand were generated for each structure After choosing the best pose we submitted 100 ns of MDs and we selected ten representative complexes with the same protocol above mentioned According to theoretical binding affinity and geometrical filters we selected the best complex in order to elucidate the catalytic mechanism by using Hybrid QMMM applying ONIOM algorithm
Our structural and thermodynamic analysis on this properly functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015) 4 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 5 Case DA Cheatham TE III Darden T Gohlke H Luo R Merz KM Jr Onufriev A Simmerling C Wang B and Woods
R The Amber biomolecular simulation programs J Computat Chem 26 1668-1688 (2005) 6 Morris G M Huey R Lindstrom W Sanner MF Belew RK Goodsell DS and Olson AJ Autodock4 and AutoDockTools4
automated docking with selective receptor flexibility J Computat Chem 16 2785-91 (2009)
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P12
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P13
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P14
De novo proteins Insights from the theoretical investigations
Tiziana Marino Mario Prejanograve Isabella Romeo Nino Russo Dipartimento di Chimica e Tecnologie Chimiche Universitagrave della Calabria Rende I-87036 Italy
email tizianamarino65unicalit
ABSTRACT
The design of de novo proteins in which both structure and function are built from scratch represents a notable challenge These enzyme-like catalysts could play a crucial role for manipulating and obtaining small molecules with prospective applications in medicine and industrial biotechnology [1] Recently this goal was achieved with the installation of the esterase activity into an entirely de novo designed homo-heptameric peptide assembly (CC-Hept) [23] In particular an artificial esterase was obtained by introduction of a catalytic triad consisting of a
glutamate a histidine and a cysteine into each -helix (CC-Hept-Cys-His-Glu) Deeper insights on the conformational behaviour and on the enzymatic activity of this properly
functionalized de novo protein could provide precious information helpful to stimulate new rationally engineered enzymes into a de novo protein framework for both already known and novel chemical transformations
At this purpose in the present study conformational properties of the CC-Hept-Cys-His-Glu engineered hydrolase were explored by means of Molecular Dynamics simulations (MDs) and molecular recognition techniques while the proposed catalytic mechanism was investigated by using a hybrid QMMM approach
REFERENCES
1 Nanda V amp Koder RL Designing artificial enzymes by intuition and computation Nature Chem 2 15-24 (2010) 2 Burton AJ Thomson AR Dawson WD Brady RL amp Woolfson DN Installing hydrolytic activity into a completely de novo
protein framework Nat Chem 8 837-844 (2016) 3 Woolfson D N Bartlett G J Burton A J Heal J W Niitsu A Thomson A R Wood C W De novo protein design how do
we expand into the universe of possible protein structures Curr Opin Struct Biol 33 16-26 (2015)
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P15
Theoretical Modelling of the Energetic and Vibrational
Properties of Photosynthesis Catalytic Cycle
Matteo Capone1
D Narzi2 L Guidoni
1
1 Universitagrave dellrsquoAquila Italia 2 Egravecole Polytechnique Fegravedegraverale de Lausanne Switzerland
Matteocaponegraduateunivaqit
ABSTRACT
The reaction centre of the Photosystem-II named Oxygen Evolving Complex is a fundamental catalyst for most of the earth life indeed is widely studied as inspiration for artificial mimic structures whom could achieve similar catalytic properties
An extensive and deepen comprehension of peculiar traits of the reaction centre is crucial for such task eventually leading to a large agreement between the all experimental data present nowadays
The crucial steps in the mechanism for oxygen evolution which is composed of 5 states named S0 to S4 resides in the supplying of substrate water molecules (S2S4) and in the bond formation between such substrate oxygens (S4)
Those phases have been studied since decades using several types of spectroscopy and since the first high resolution crystallographic structure [1] with theoretical methods
Using QMMM dynamics and gas phase models we built a comprehensive pathway of intermediate steps starting from the S2 state up to the O-O bond formation [2-58] which involves interconversions between open and closed cubane isomers and the binding of a water molecule to the cluster
With different energy calculation approach we estimated the thermodynamic of such path to clarify a possible preferential reaction way for the molecular oxygen evolution
Furthermore after the characterization of the Mn-core vibrational modes in the S2 state isomers by Vibrational Density Of State of QMMM dynamics [6] in order advance into the interpretation of the experimental infrared data available for the metastable S1 S2 and S3 states [7] we calculated vibrational properties from QMMM dynamics through dipole-dipole autocorrelation function and also using static models with Normal Mode Analysis
In particular to help the interpretation of the experimental data in the middle and low-frequency region (1800-1100 and 700-400 cm-1) we propose a decomposition of the dipole calculated with QMMM-MD The Mn4CaO5 moiety is separated in to diamonds each one involving four atoms and the cluster-ligands in single ligand dipole
The spectral signatures arising from this analysis promise to be a useful insight to assign experimentally identified bands to specific molecular motions
REFERENCES
1 Umena et al Nature 2011 473 55--60 2 Bovi D Narzi D Guidoni L Angew Chem Int Ed 2013 52 11744ndash11749 3 Narzi D Bovi D Guidoni L Proc Natl Acad Sci USA 2014 111 8723ndash8728 4 Capone M Bovi D Narzi D Guidoni L Biochemistry 2015 54 (42) pp 6439ndash6442 5 Capone M Narzi D Bovi D Guidoni L J Phys Chem Lett 2016 7 (3) pp 592ndash596 6 Bovi D Capone M Narzi D Guidoni L Biochim Biophys Acta 2016 1857(10) 1669-1677 7 Debus R J Biochim Biophys Acta 2015 1847(1) 19-34 8 Narzi D Capone M Bovi D amp Guidoni L Chem Eur J 2018 DOI 101002chem201801709
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P16
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P17
Excitonic State evolution of DNA Stacked Thymines Different Decay Paths Account for Ultrafast and Longer
(gt100 ps) Deactivations
Irene Contia Marco Garavelli a
a Dipartimento di Chimica Industriale ldquo Toso Montanarirdquo Universita di Bologna Viale del Risorgimento 4 I-40136
Bologna Italy email Irenecontiuniboit
ABSTRACT
The exciton decay paths for two stacked quantum mechanical thymines inside a solvated DNA duplex described at the
molecular mechanics level are mapped using a hybrid CASPT2CASSCFMM protocol that accounts for steric
electronic and electrostatic interactions within the nucleobases native environment Asymmetric stacking between
nucleobases causes differences in the classical ππ monomer-like ring puckering decay paths accounting for distinctive
excited state lifetimes spanning the sub-ps to sub-ns time window1
Feasible base-pair CT states and their related electronminus proton transfer decay paths could also play a role in the
excited-state wide-ranging lifetimes leading to rare tautomers formations accounting for mispairing and possibly at
the origin of DNA mutations2
REFERENCES
1 I Conti e M Garavelli Evolution of the Excitonic State of DNA Stacked Thymines Intrabase ππrarrS0 Decay Paths Account for Ultrafast (Subpicosecond) and Longer (gt100 ps) Deactivations laquoTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERraquo 2018 9 (9) pp 2373ndash2379
2 Isaac J Kimsey et al Dynamic basis for dGbulldT misincorporation via tautomerization and ionization laquoNATUREraquo 2018 554 pp 195
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P18
Ionic Liquids and Proton Transfer A Computational Study to Understand Dynamic Processes
Andrea Le Donne1 Enrico Bodo1
1 Chemistry department University of Rome ldquoLa Sapienzardquo Rome Italy andrealedonneuniroma1it
9 ABSTRACT
Ionic Liquids (IL) are pure ionic compounds liquid under room conditions The combination of their liquid state and complete ionization gives them interesting and particular characteristics negligible vapor pressure excellent chemical and thermal stability and the possibility of tuning their physical proprieties adding different chemical groups to the molecular ions1 The presence of strong Coulomb interactions between the ionic pairs makes these kind of materials extremely viscous so that the conductivity of pure IL is low because the drift of ions is hindered by the electrostatic interactions
We are studying the possibility to improve conductivity of IL bypassing the slow drift of ions by exploiting proton transfer (PT) between anions2 We chose a specific subset of IL consisting of choline and anionic amino acids In particular we focused on amino acids with a second acid group on the side chain this is fundamental because the proton of carboxylic group is ―consumed during the synthesis
First of all extensive and accurate ab initio calculations were performed in order to find the best candidate for proton transfer3 The criteria for the selection of candidates were having small energy barriers and near resonant PT reactions where the energies between reagents and products across the PT should be as similar as possible In this way PT should be a dynamic process with the possibility of the proton to migrate into the liquid
Based on upon criteria four candidates have been chosen to be studied by extensive ab initio molecular dynamics and to explore their dynamic properties with particular attention on the mobility of proton
REFERENCES
1 Rogers RD and Seddon KR ―Ionic LiquidsmdashSolvents of the future Science 302 (5646) 792-793 (2003) 2 Campetella M Montagna M Gontrani L Scarpellini E and Bodo E ―Unexpected proton mobility in the bulk phase of cholinium-
based ionic liquids new insights from theoretical calculations Phys Chem Chem Phys 19 (19) 11869-11880 (2017) 3 Le Donne A and Bodo E ―Isomerization patterns and proton transfer in ionic liquids constituents as probeb by ab-initio computetion
J Mol Liq 249 1075-1082 (2018)
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P19
Simulating 2D IR-UV pump-probe
spectra by means of time-independent
vibronic calculations
Franco Egidi1 Vincenzo Barone 1
1 Scuola Normale Superiore 56126 Pisa Italy
francoegidisnsit
ABSTRACT
In some pump-probe experiments an Infra-Red (IR) pump pulse causes a vibrational transition from the ground vibrational state to an excited vibrational state The frequency of the pump pulse can be tuned to select only certain vibrational modes [12] The pump pulse is followed by a probe which lies in the Ultra-Violet or visible (UV-vis) part of the spectrum thus causing an electronic transition within the system Theoretically electronic transitions are often modeled by considering the effect of the radiation on the electronic degrees of freedom only and the resulting absorption (or emission) spectrum is composed of discrete peaks which can be broadened by means of a given lineshape function (often Gaussian or Lorentzian) with an empirical broadening This approximation however neglects the important contributions from the vibrational degrees of freedom of the molecule which constitute the vibronic signature of the spectrum and in a one-photon UV absorption spectrum can often be the main source of the bandsrsquo broadening and specific bandshape which is often not symmetric In pump-probe experiments vibronic effects cannot be neglected as the experiment highlights precisely the differences in the vibrational manifolds of the ground and excited electronic potential energy surfaces (PES) which can be appreciated in the difference-spectrum obtained small differences in vibrational energies can result in positive and negative peaks We present a method for simulating such experiments by means of time-independent vibronic calculations that fully take the differences in the PESs into account [2] and show results for transition metal complexes which were previously studied experimentally
REFERENCES
1 TL Courtney et al J Phys Chem Lett 6 (2015) 1286 2 TAA Oliver et al Proc Natl Acad Sci USA 111 (2014) 10061 3 J Bloino et al Int J Quantum Chem 116 (2016) 1543
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P20
Rapid evaluation of dynamic disorder in organic semiconductors
Alessandro Landi1 Andrea Peluso1 Alessandro Troisi2
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Chemistry University of Liverpool Liverpool L69 3BX United Kingdom alelandi1unisait
ABSTRACT
Organic molecular semiconductors are currently widely used in modern optoelectronic devices [1] such as organic light emitting diodes bulk heterojunction solar cells and field effect transistors Research towards the discovery of better semiconductors ie those showing higher charge mobility is very active and many authors are advocating the use of computer-aided materials discovery [2] to accelerate progresses in this field
Unfortunately while for inorganic covalently bonded materials the band theory is well established there is still a debate about the most appropriate theoretical approach to model charge transport in organic semiconductors Indeed it has been pointed out that possibly neither the hopping nor the band-like mechanism is adequate for treating charge transport for the class of high-mobility molecular semiconductors ndash ie those displaying mobilities exceeding 1 cm2 Vminus1 sminus1 [3]
Several alternative models based on the observation that the transfer integral undergoes large fluctuations because of thermal motions also known as dynamic disorder have been developed In particular Fratini et al proposed a method based on the evaluation of a transient localization [4] that when applied to a family of realistic semiconductors demonstrated excellent predictive power
The dynamic disorder is due to the strong modulation of the transfer integral by low frequency molecular phonons ie it is a manifestation of the non-local electron-phonon coupling a property that is computationally expensive to evaluate and so far prevented the study of this property on large datasets of molecules Here we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors starting from their crystalline structure [5] The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation where each molecule is assumed to oscillate independently with the great advantage of separating effectively the internal (intramolecular vibrations) and external (intermolecular vibrations) degrees of freedom Despite the severe approximations our method leads to results in excellent agreement with data obtained with more accurate approaches [6]
REFERENCES
1 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey and J-L Breacutedas Chem Rev 107 926-952 (2007) 2 A V Akimov and O V Prezhdo Chem Rev 115 5797ndash5890 (2015) 3 S Fratini S Ciuchi D Mayou G T De Laissardiegravere and A Troisi Nat Mater 16 998ndash1002 (2017) 4 S Ciuchi and S Fratini Phys Rev B 86 245201 (2012) 5 A Landi and A Troisi under review 6 R S Saacutenchez-Carrera P Paramonov G M Day V Coropceanu and J L Breacutedas J Am Chem Soc 132 14437ndash14446 (2010)
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P21
Hole Mobility in Organic Semiconductors A Second-Order Cumulant Approach
Alessandro Landi1 Raffaele Borrelli2 Andrea Peluso1
1 Dipartimento di Chimica e Biologia Adolfo Zambelli Universitagrave di Salerno Via Giovanni Paolo II I-84084 Fisciano (SA) Italy
2 Department of Agricultural Forestry and Food Science University of Torino Via Leonardo da Vinci 44 I-10095 Grugliasco Italia
alelandi1unisait
ABSTRACT
Charge transport in molecular systems is of paramount importance both for understanding important biochemical processes [1] such as photosynthesis respiration and DNA oxidative damage and for designing new molecular materials for modern optoelectronic devices [2] In the case of molecular semiconductors one of the key properties to be compared with experimental data is the hole mobility and in particular its anisotropy ie the dependence of charge mobility on the orientation of the conductive channel relative to the crystallographic axes
The computational methodology for predicting charge mobility must be related to a mechanism of charge transport in the framework of a simple hopping mechanism hole mobility can be evaluated by a master equation approach with rate constants which are usually obtained either by Marcusrsquo semiclassical approach or by the Fermi Golden Rule (FGR) Both methods suffer from limitations since the former does not account for tunnelling effects and the latter a full quantum mechanical approach at the first order of time dependent perturbation theory is not well suited for ultrafast processes because of the use of the integral representation of the delta function
Herein we use a recently developed approach based on the second-order cumulant (SOC) expansion of the reduced density matrix [3] for evaluating hole hopping rates [4] in homodimers of some of the most studied organic semiconducting molecules It is shown that the SOC approach predicts populations decay in good agreement with those predicted by the numerical solution of the time dependent Schroumldinger equation [5] and leads to anisotropic mobility in good agreement with experimental results even for ultra-fast transitions where FGR fails Moreover the temperature dependence of hole mobility predicted by SOC approach is in line with experimental findings while Marcusrsquo formula leads to wrong temperature dependence [6]
REFERENCES
1 J C Genereux J K Barton Chem Rev 110 1642-1662 (2010) 2 V Coropceanu J Cornil D A da Silva Filho Y Olivier R Silbey J-L Breacutedas Chem Rev 107 926-952 (2007) 3 R Borrelli A Peluso J Chem Theory Comput 11 415-422 (2015) 4 A Landi R Borrelli A Capobianco A Velardo A Peluso J Chem Theory Comput 14 1594minus1601 (2018) 5 Borrelli Capobianco Landi Peluso Phys Chem Chem Phys 17 30937-30945 (2015) 6 A Landi and A Peluso manuscript in preparation
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P22
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P23
Theoretical Study on the Circular Dichroism of Chiral Bimetallic Clusters Ag-Au
Marco Medves1 Mauro Stener1 Giovanna Fronzoni1 Daniele Toffoli1 Alessandro Fortunelli2 Luca Sementa2
1 DSCF Universitagrave di Trieste 2 CNR-ICCOM Pisa
email marcomedvesvirgilioit
ABSTRACT
The POLTDDFT algorithm [1] recently implemented within ADF has been employed to calculate photoabsorption and CD of silver-gold bimetallic chiral clusters The POLTDDFT has proven very efficient to treat accurately large systems without symmetry In particular the optical properties of the cluster [Ag24Au(BINAS)4(DMBT)10]
- have been studied in detail A preliminary optimization identified two structures of comparable energies which were both considered for the study of the optical properties The calculated spectra have been analysed in terms of a recent scheme based on fragments [2] and specific spectral feature have been studied in terms of Individual Component Mapping (ICM) [3] for both oscillator strength and rotation strength Collective behaviours as well as constructivedescructive interference effects have been identified The dichroic response of the cluster has proven very sensitive to the ligand conformations this suggests further studies in order to include ligand conformational freedom in the computational model
REFERENCES
1 Oscar Baseggio Giovanna Fronzoni and Mauro Stener J Chem Phys 143 (2015) 024106 2 Luca Sementa Giovanni Barcaro Oscar Baseggio Martina De Vetta Amala Dass Edoardo Apragrave Mauro Stener Alessandro
Fortunelli J Phys Chem C 121 (2017) 10832 ndash 10842 3 Le Chang Oscar Baseggio Luca Sementa Daojian Cheng Giovanna Fronzoni Daniele Toffoli Edoardo Apragrave Mauro Stener and
Alessandro Fortunelli Journal of Chemical Theory and Computation 14 (2018) 3703
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P24
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P25
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
P27
P26
Combined Orbital-spaceReal-space Analysis of Chemical Bonding through Virtual Reality
Andrea Salvadori1 Marco Fusegrave1 Giordano Mancini1 Sergio Rampino1 Vincenzo Barone1
1 SMART Laboratory Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa sergiorampinosnsit
ABSTRACT
Based on state-of-the-art virtual-reality technology and a recently devised combined orbital-spacereal-space scheme for the analysis of the electron-charge rearrangement occurring upon bond formation we have developed a virtual laboratory for immersive analysis of chemical bonding1 The analysis scheme which couples the natural orbitals for chemical valence (NOCV)2 with a suitably defined integration in physical space3 is capable of singling out chemically meaningful bond components along with quantitative estimates of the related charge-flow profiles and has been recently extended to the four-component fully relativistic framework4 The potential of the developed machinery and the robustness of the analysis scheme will be illustrated through applications including probing the chemical character of superheavy elements5 and investigating the relation between the σ-donorπ-acceptor abilities of ligands and selected spectroscopic observables in coordination complexes6-8
REFERENCES
1 A Salvadori M Fusegrave G Mancini S Rampino V Barone J Comput Chem 2018 in press 2 A Michalak M Mitoraj T Ziegler J Phys Chem A 2008 112 1933-1939 3 G Bistoni S Rampino F Tarantelli L Belpassi J Chem Phys 2015 142 084112 (9pp) 4 M De Santis S Rampino HM Quiney L Belpassi L Storchi J Chem Theory Comput 2018 14 1286-1296 5 S Rampino L Storchi L Belpassi J Chem Phys 2015 143 024307 (8 pp) 6 G Bistoni S Rampino N Scafuri G Ciancaleoni D Zuccaccia L Belpassi F Tarantelli Chem Sci 2016 7 1174-1184 7 M Fusegrave I Rimoldi E Cesarotti S Rampino V Barone Phys Chem Chem Phys 2017 19 9028-9038 8 M Fusegrave I Rimoldi G Facchetti S Rampino V Barone Chem Commun 2018 54 2397-2400
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