Electronic Energy Transfer: Localized Operator Partitioning of Electronic Energy in Composite Quantum Systems

TL;DR

This paper introduces a Hamiltonian-based method using localized projection operators to define electronic energy in quantum subsystems, enabling precise analysis of energy transfer in complex molecular systems.

Contribution

It presents a novel localized operator partitioning scheme that accurately defines electronic energy in strongly interacting and isolated quantum fragments.

Findings

The method correctly recovers F"orster and Dexter energy transfer limits.

Numerical simulations demonstrate the approach's effectiveness in modeling energy and charge transfer.

Decoherence effects significantly influence transfer dynamics in model 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 leads to the proper electronic energy at all internuclear distances, including the case of separated fragments, and reduces to the well-known Forster 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.