A Subsystem TDDFT Approach for Solvent Screening Effects on Excitation Energy Transfer Couplings

TitleA Subsystem TDDFT Approach for Solvent Screening Effects on Excitation Energy Transfer Couplings
Publication TypeJournal Article
Year of Publication2010
AuthorsNeugebauer, J, Curutchet C, Munoz-Losa A, Mennucci B
JournalJournal of Chemical Theory and Computation
Pagination1843 - 1851
Date Published2010
ISBN Number1549-9618
Keywordsbasis-sets, charge-transfer excitations, constrained electron-density, density-functional theory, excited-states, kohn-sham equations, lh2, molecular scale interpretation, purple bacteria, solvated bichromophoric systems
AbstractWe present a QM/QM approach for the calculation of solvent screening effects on excitation-energy transfer (EET) couplings. The method employs a subsystem time-dependent density-functional theory formalism [J. Chem. Phys. 2007, 126, 134116] and explicitly includes solvent excited states to account for the environmental response. It is investigated how the efficiency of these calculations can be enhanced in order to treat systems with very large solvation shells while fully including the environmental response. In particular, we introduce a criterion to select solvent excited states according to their approximate contribution weight to the environmental polarization. As a model system, we investigate the perylene diimide dimer in a water cluster in comparison to a recent polarizable QM/MM method for EET couplings in the condensed phase [J. Chem. Theory Comput. 2009, 5, 1838]. A good overall agreement in the description of the solvent screening is found. Deviations can be observed for the effect of the closest water molecules, whereas the screening introduced by outer solvation shells is very similar in both methods. Our results can thus be helpful to determine at which distance from a chromophore environmental response effects may safely be approximated by classical models.