A self-consistent quantum master equation approach to molecular transport

TL;DR

This paper introduces a self-consistent, time-local quantum master equation approach for modeling electron transport in molecular junctions, improving the accuracy of steady-state predictions over previous methods.

Contribution

It develops a self-consistent, time-local generalized quantum master equation using backward Redfield evolution, enhancing the modeling of molecular transport.

Findings

Accurately reproduces steady-state density matrix and currents

Less accurate for higher moments like noise

Provides a computationally feasible approximation

Abstract

We propose a self-consistent generalized quantum master equation (GQME) to describe electron transport through molecular junctions. In a previous study [M.Esposito and M.Galperin. Phys. Rev. B 79, 205303 (2009)], we derived a time-nonlocal GQME to cure the lack of broadening effects in Redfield theory. To do so, the free evolution used in the Born-Markov approximation to close the Redfield equation was replaced by a standard Redfield evolution. In the present paper, we propose a backward Redfield evolution leading to a time-local GQME which allows for a self-consistent procedure of the GQME generator. This approach is approximate but properly reproduces the nonequilibrium steady state density matrix and the currents of an exactly solvable model. The approach is less accurate for higher moments such as the noise.