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Konstantin
V. Odintsov, Tatiana M. Domratcheva
Multiconfiguration quantum chemistry calculations for
describing photoinduced DNA repair
Abstract
Abstract.Electronicexcitationenergiesanddipolemoments have been computed using multiconfiguration CASSCF method further corrected to the second order
perturbation theory XMCQDPT2
for a molecular cluster modeling the active site of (6–4) photolyase containing
a thymine-thymine (6–4) photoproduct. Asetofmodelsisconsideredinwhichtheexcitation energies
change in a wide range since anionic phosphate groups of the photoproduct and
cofactor flavin adenine dinucleotide (FADH–) are included in the
models. The results demonstratethataccountforsolventeffectsusing a PCM model reproduces the shielding of negative charges of the phosphate
groups by the environment of the active site. The limits of the two-state model for estimating the electronic coupling matrix
elements of the electron transfer reactions are investigated. The electronic
coupling matrix elements may become overestimated due to the presence of a
bright excited state in the flavin excitation spectrum.
Key words: DNA photolyase, (6–4) photoproduct,
electron transfer, quantum-chemistry calculations XMCQDPT2, solvent model PCM,
electronic coupling, Marcus theory, generalized Mulliken–Hush scheme
Copyright (C) Chemistry Dept., Moscow State University, 2002
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