Consistent treatment of coherent and incoherent energy transfer dynamics using a variational master equation

TL;DR

This paper introduces a versatile variational master equation approach for modeling energy transfer dynamics, effectively bridging the gap between different regimes and incorporating environmental effects.

Contribution

It develops a new variational transformation-based master equation that accurately describes energy transfer across various coupling strengths and environmental conditions.

Findings

Reduces to known models in specific limits

Valid across a wide range of parameters

Includes environmental correlations and non-equilibrium effects

Abstract

We investigate the energy transfer dynamics in a donor-acceptor model by developing a time-local master equation technique based on a variational transformation of the underlying Hamiltonian. The variational transformation allows a minimisation of the Hamiltonian perturbation term dependent on the system parameters, and consequently results in a versatile master equation valid over a range of system-bath coupling strengths, temperatures, and environmental spectral densities. While our formalism reduces to the well-known Redfield, Foerster and polaron forms in the appropriate limits, in general it is not equivalent to perturbing in either the system-environment or donor-acceptor coupling strengths, and hence can provide reliable results between these limits as well. Moreover, we show how to include the effects of both environmental correlations and non-equilibrium preparations within the formalism.