Specific solvation effects on electron transfer

Abstract

This article focuses on the effects of specific solvation on electron transfer (ET) reactions and illustrates how differing configurations of solvent molecules can change the ET rate. The evolution of the ET system is given by a recently developed dynamical model for ET [1]. The dynamical model allows for evolution of the ET system dynamically coupled to the outer solvent and the intramolecular degrees of freedom. The evolution of the ET system is followed in direct time using time-dependent statistical density operators. The initial state of the ET system is selected by a variational scheme, thereby determining an appropriate time-dependent statistical density operator for the initial state. The electronic subsystem is treated by a full ab-initio electronic Hamiltonian and allows for a detailed description of the electronic structure. The ET system consists of a donor, an acceptor, and a selection of solvent/bridge molecules; this encounter is surrounded by a dielectric medium [1, 2]. The actual calculations concern an ET system consisting of benzene anion radical as donor, benzene as acceptor, and three water molecules in the first solvation shell. These calculations show how important specific solvation of the donor-acceptor complex is for the ET process. The ET probability can be increased or decreased depending on the configuration of the water molecules.