IV characteristics of molecular wires in the presence of intramolecular vibrational energy redistribution

Various interaction mechanisms may contribute to the current-voltage (ITI) characteristics of a single molecule embedded between two nano-electrodes. Here, we focus on a microscopic modeling of intramolecular vibrational energy redistribution (IVR) and its influence on the formation of a stationary current. The computations are based on a generalized master equation approach, restricted to weak molecule-lead coupling as well as weak IVR-coupling of a primary reaction coordinate to a thermal bath of secondary coordinates. The pronounced dependence of the IV characteristics on the properties of the reaction coordinate such as its reorganization energy upon charging of the molecule is demonstrated. Furthermore, the shortcomings of a relaxation time model of IVR are underlined. (c) 2006 Elsevier B.V. All rights reserved.