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Computational Chemistry 518 CHIMIA 2012, 66, No. 7/8 Computational Chemistry doi:10.2533/chimia.2012.518 Chimia 66 (2012) 518–531 © Schweizerische Chemische Gesellschaft ComputationalChemistry ComputationalChemistry Computational Chemistry,Talk 155 Computational Chemistry,Talk 156 ExploringPhotoinduced Intermolecular Electrontransferwith Local Control Theory in Trajectory-based Nonadiabatic Dynamics Molecular Dynamics Simulations B. F. E. Curchod1,T.J.Penfold1,2,3,U.Rothlisberger1,and I. Tavernelli1 A. Gamiz-Hernandez1,E.Vauthey2,M.Meuwly1 1Laboratory of Computational Chemistry and Biochemistry, Ecole Poly- technique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland 1UniversityofBasel/DepartmentofChemistry, Klingelbergstr. 80, CH-4055 2Laboratoire de Spectroscopie Ultrarapide, Ecole Polytechnique Fédérale de Basel, Switzerland Lausanne, CH-1015 Lausanne, Switzerland 2UniversityofGeneva/DepartmentofPhysicalChemistry, 30 quaiErnest- 3SwissFEL, Paul Scherrer Inst., CH-5232 Villigen, Switzerland. Ansermet, CH-1211 Geneva 4, Switzerland In the last years, linear-response time-dependent density functional theory (LR-TDDFT) has become widely used for the calculation of vertical elec- Understandingthe dynamics of photoinduced chemical processes involving tronic excitation energies of medium to large size molecular systems in gas electron transfer(ET)isacrucialstep for the designofnew technologies and condensed phases. In addition, excited state LR-TDDFT forces and such as efficient solar energy conversion devices. Photoinduced ET pro- nonadiabatic couplings have also been implementedindifferent software cesses have been investigated for some time [1], nevertheless thereare still packages, which enables LR-TDDFT based ab initio molecular dynamics severalquestionsregarding intermolecular ET reactions such as theoccur- approaches for the study of photochemical reactions. renceoflongdistancereactions andthe ChargeSeparation(CS)products. Manyexperiments have corroborated Marcus theory[2] for ET, however, Here, we present adevelopment of aLR-TDDFTtrajectory surface hopping most of these models aresimplifications as theyconsiderthe reactants as scheme that couples nuclear and electronic degrees of freedom with an ex- spheres andquantities such as the reorganizationenergyare computed using ternal electromagnetic field [1,2]. This further allows the on-the-fly calcula- continuum models for the solvent. Molecular Dynamics (MD)simulations tion of an electric pulse, which controls the population transfer between of photoinduced reactions have the potential to provide abetterinsightto electronic states using local control theory. This method is applied to the explore for example, at whatdistance CS takesplace, what is the nature of molecule lithium fluoride and the results are compared with nuclear quan- the primaryion pair product, computationofmore accurate reorganization tum dynamics using the MCTDH method. In addition, we will present an energies basedonanexplicitsolvent models andhow intermolecularinter- example of how acontrolled pulse can trigger aphotochemical reaction like actions influencethe orientations of the reactants. proton transfer in 4-hydroxyacridine. This research will presentsome resultsfromMDSimulations of bimolecu- [1] I. Tavernelli, B. F. E. Curchod, and U. Rothlisberger, Phys. Rev. A lar photoinduced ET reactions [1], in particularthe Perylene- 2010, 81,052508. Dimethylaniline system.Weinvestigate how the solvent adoptsdifferent [2] B. F. E. Curchod, T. J. Penfold, U. Rothlisberger, and I. Tavernelli, configurations as well as possible pathwaysfor CS. These conformations Phys. Rev. A 2011, 84,042507. areusedfor quantum-chemical calculations to generateabsorption/emission spectra,helping to explain experimentalresults. [1] E. Vauthey, J. Photochem. Photobiol. A, 2006,179, 1. [2] R. A. Marcus andN.Sutin, Biochim. Biophys. Acta, 1985,811, 265. ComputationalChemistry ComputationalChemistry Computational Chemistry,Talk 157 Computational Chemistry,Talk 158 EffectofProtein EnvironmentonExcitation EnergyofRetinal Spectral Tuning in Rhodopsin Early Photointermediates Xiuwen Zhou1,Tomasz A. Wesolowski2 Pablo Campomanes,Ursula Röthlisberger 1 University of Geneva,Department of Physical Chemistry, Quai Ernest- Ecole Polytechnique Fédérale Lausanne, CH-1015, Lausanne, Switzerland Ansermet 30, CH-1211 Geneva,Switzerland The visual pigment rhodopsin is ahighly specialized member of the GPCR Retinalisachromophoreofkey importanceinthe photochemical process family found in vertebrate rod cells. Rhodopsin is able to capture and con- responsiblefor animalvision,which begins with cis-trans vert light into achemical signal, in what constitutes the first step of the vi- photoisomerization(seeFigure1)ofretinal bound to opsin(aprotein)[1]. sion. The photoinduced isomerization of its natural ligand (11-cis retinal) The absorbtion spectrumofthe chromophoreisaffectedbythe proteinto inside the binding pocket initiates acascade of conformational changes that whichitisbound. The long range objectiveofthisproject is thedevelop- leads ultimately to receptor activation and subsequentdownstream signal- ment of an accurate modelingtechnique to predictthe effect of proteinmu- ing. Several spectroscopically distinguishable intermediates involved in the tations on theabsorption spectra of retinal.Suchtechnique couldbeusedto early steps of this photoactivation mechanism have been detected, and the help designing proteinmutations leadingtodesired spectralpropertiesofthe structures of some of them have been determined. However, the complete chromophore. Theappliedcomputationalmethod belongs to thecategoryof knowledge of the factors that selectively modulate retinal absorption during multi-levelsimulations andisbased on Frozen-Density EmbeddingTheory the initial events of the visual cascade is far from being achieved and, there- (FDET) [2-4]. Theresults of thefirst stage of this project will be reported fore, adirect relation between the structural changes caused by the relaxa- concerning: a) developmentofanefficient method to generatethe frozen tion of the photoexcited chromophoreupon isomerization and the corre- density forFDETcalculations developedbased on comparison between sponding optical shifts observed for the intermediates involved in the very benchmark supermolacularab-initio results [5]obtainedfor small models of early steps of the rhodopsin photocycle has not been established yet. the environment, andb)modelingthe effect of point mutations in proteins In this contribution, Iwill show how acombined strategy based on the com- on theabsorption spectra. putation of absorption energies, using the ZINDO/Ssemi-empiricalmethod, for astatistically relevant number of thermally sampled configurationsex- Figure 1.Photoisomerizationofretinal tracted from QM/MM trajectoriescan be used to establish aone-to-one cor- respondence between the structures of the different intermediates involved in the very early steps of the rhodopsin photocycle and their optical spectra. [1]R.Hubbard andG.Wald, J. Gen. Physiol., 1952-53,36, 269. The analysis of the results clarify the role played by some of the residues located in the protein-binding pocket as well as the importance of the struc- [2]T.A. Wesolowski andA.Warshel, J. Phys. Chem., 1993, 97,8050. tural features and conformation of the chromophore on the spectral shifts [3]T.A. Wesolowski, Computational Chemistry: ReviewsofCurrent observed between the intermediates. They also permit the identification of Trends,J.Leszczynski,Ed. WorldScientific, 2006, 10,1. the structural parameters that better describe the different transitions leading [4]T.A. Wesolowski, Phys. Rev. A, 2008, 77,012504. from dark- to lumi-rhodopsin, therefore allowing the characterization of the [5]V.R.I.Kaila,R.Send, D. Sundholm, J. Phys. Chem.B,2012, 116,2249. distinct states. Computational Chemistry CHIMIA 2012, 66, No. 7/8 519 Computational Chemistry Computational Chemistry Computational Chemistry,Talk 159 Computational Chemistry,Talk 160 Unravelling the electronic structureofmolecules with density-only Exploring the Limits of Modern Density Functional Approximations based detectors for Interaction Energies Piotr de Silva1,2,Jacek Korchowiec1,Tomasz A. Wesolowski2 StephanN.Steinmann and ClemenceCorminboeuf 1K. Guminski´ Department of Theoretical Chemistry,Faculty of Chemistry, Laboratory for Computational MolecularDesign, Institute of Chemical Jagiellonian University,R.Ingardena 3, 30-060 Krakow´ ,Poland Sciences and Engineering,Ecole Polytechnique Fédérale de Lausanne, 1015 2Universited´ eGenev` e, Departement´ de Chimie Physique 30, quai Lausanne, Switzerland Ernest-Ansermet, CH-1211 Genev` e4,Switzerland Charge transfer complexes and charged radical π-dimers span the field The Electron Localization Function (ELF) [1-3] has provedtobeanexcep- of organicelectronics,makingtheircharacterization of considerable interest. Theelectronic structure of charge transfer complexes is highly tionally useful concept in the elucidation of bonding patterns in molecules and challenging.1 We demonstrate that standard densityfunctionals fail to solids. The major drawbacks of ELF are its orbital dependence and the use of accurately describeinteraction energies of charge-transfer complexes not the homogeneous electron gasareference. In this contribution, we propose only because of the missing long-range exchange, as generally assumed, but an entirely newparadigm for the clarification of the electronic structure in predominantlybecauseofthe ubiquitously present, yet neglected dispersion terms
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