Estimation of Electronic\nCoupling for Photoinduced\nCharge Separation and Charge Recombination Using the Fragment Charge\nDifference Method

Abstract

Photoinduced electron transfer reactions play an important\nrole\nin chemistry, biochemistry, and material sciences. Electronic coupling\nof donor and acceptor is a key parameter that controls the rate of\ncharge separation and charge recombination processes. The fragment\ncharge difference (FCD) method is extended to calculate the electronic\ncouplings and diabatic energies for the photoinduced reactions. It\nis shown that FCD provides consistent values of the ET parameters\nfor any 3-state model system. We compare the matrix elements obtained\nwithin the 2- and 3-state treatment for different situations and suggest\nhow to check adiabatic states included in the diabatization procedure.\nTwo examples demonstrate the use of the FCD method in combination\nwith MS-CASPT2 calculations to derive the ET parameters.