Full-electron calculation of effective electronic couplings and excitation energies of charge transfer states: Application to hole transfer in DNA pi-stacks.
In this work I develop and apply a theoretical method for calculating effective electronic couplings (or transfer integrals) between redox sites involved in hole or electron transfer reactions. The resulting methodology is a refinement and a generalization of a recently developed approach for transfer integral evaluation. In fact, it holds for any overlap between the charge-localized states used to represent charge transfer (CT) processes in the two-state model. The presented theoretical and computational analyses show that the prototype approach is recovered for sufficiently small overlaps. The method does not involve any empirical parameter. It allows a complete multielectron description, therefore including electronic relaxation effects. Furthermore, its theoretical formulation holds at any value of the given reaction coordinate and yields a formula for the evaluation of the vertical excitation energy (i.e., the energy difference between the adiabatic ground and first-excited electronic states) that rests on the same physical quantities used in transfer integral calculation. In this paper the theoretical approach is applied to CT in B-DNA base dimers within the framework of Density Functional Theory (DFT), although it can be implemented in other computational schemes. The results of this work, as compared with previous Hartree-Fock (HF) and post-HF evaluations, support the applicability of the current implementation of the method to larger pi-stacked arrays, where post-HF approaches are computationally unfeasible.
Migliore
Agostino
A
Department of Chemistry and Center for Molecular Modeling, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, USA.
D002245:Carbon Dioxide / Q000737:chemistry; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry*; D019281:Dimerization; D004579:Electron Transport / Q000502:physiology*; D004581:Electronics; D004583:Electrons / Q000009:adverse effects*; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D011789:Quantum Theory; D055672:Static Electricity; D013598:Systems Theory
D002245:Carbon Dioxide; D004247:DNA