Superexchange versus sequential long range electron transfer; density matrix pathways in Liouville space

Abstract

Two important issues in the theory of electron transfer: the competition between superexchange and sequential mechanisms, and the contributions of intermediate bridge states to the propagation from donor to acceptor are addressed by formulating the problem using the density matrix. The evolution of the density matrix allows the introduction of Liouville space pathways. By following the time dependence of the populations and coherences of the system (diagonal and off-diagonal elements of the density matrix), we identify the relevant pathways and the electron transfer mechanism.