Hierarchical quantum master equation approach to charge transport in molecular junctions with time-dependent molecule-lead coupling strengths

Time-dependent currents in molecular junctions can be caused by structural fluctuations or interaction with external fields. In this paper, we demonstrate how the hierarchical quantum master equation approach can be used to study time-dependent transport in a molecular junction. This reduced density matrix methodology provides a numerically exact solution to the transport problem including time-dependent energy levels, molecule-lead coupling strengths and transitions between electronic states of the molecular bridge. Based on a representative model, the influence of a time-dependent molecule-lead coupling on the electronic current is analyzed in some detail.