Heat currents in a two channel Marcus molecular junction

Abstract

We present a theoretical analysis of heat transfer in a single-molecule junction where the bridge is simulated by a three-state model with two possible transport channels for electrons. Interactions between electrons on the bridge and phonons in the nuclear environment are supposed to be strong, so that Marcus-type processes predominate in the electron transport. It is shown that asymmetric coupling between the bridge states and electrodes and/or asymmetric distribution of the bias voltage over the system together with characteristics of the environmental reorganization and relaxation processes accompanying electron transport may result in qualitative changes in the behavior of steady state heat currents. These changes are controlled by the same mechanism as NDR effect manifested in the charge current under similar conditions. Also, we analyze the energy balance in single-molecule junctions assuming that energy levels of the molecule are slowly driven by an external force.