Electronic energy transfer: Localized operator partitioning of electronic energy in composite quantum systems

Abstract

A Hamiltonian based approach using spatially localized projection operators is introduced to give precise meaning to the chemically intuitive idea of the electronic energy on a quantum subsystem. This definition facilitates the study of electronic energy transfer in arbitrarily coupled quantum systems. In particular, the decomposition scheme can be applied to molecular components that are strongly interacting (with significant orbital overlap) as well as to isolated fragments. The result defines a consistent electronic energy at all internuclear distances, including the case of separated fragments, and reduces to the well-known Förster and Dexter results in their respective limits. Numerical calculations of coherent energy and charge transfer dynamics in simple model systems are presented and the effect of collisionally induced decoherence is examined.

Vibronic Effects on Rates of Excitation Energy Transfer and Their Temperature Dependence

“…Additionally, the overlap of the densities of the donor and acceptor fragments could become non-negligible. Electronic couplings calculated using a localized operator partitioning method , address both issues. If the electronic coupling is not too strong, as the cases considered in the present work, the formalism reduces to the Förster limit …”

An efficient implementation of the localized operator partitioning method for electronic energy transfer

“…The local Hamiltonian H p was designed in Ref. 2, guided by three principles: (1) the subsystem energy E p must be real, (2) the energies E p must reduce to the correct component energies for infinitely separated fragments, and (3) the operator H p must be symmetric with respect to electron exchange. The last condition ensures that E p written as E p = Tr[DH p ] is invariant with respect to electron exchange, since the electron density D = |Ψ(t) Ψ(t)| is symmetric with respect to electron interchange.…”