Effects of atomic-scale contacts on transport properties through single molecules – ab initio study

Abstract

Using the RTM/NEGF method, which is a first-principles calculation tool for the quantum transport through nanostructures between electrodes, we study the effects of atomic-scale contacts on the transport properties through single molecules. Electronic states and current–voltage ( I– V) characteristics are investigated in various contact conditions with and without single molecules between electrodes. We find that similar nonlinear behaviors appear in the I– V characteristics. Such nonlinear behaviors are determined not only by the HOMO–LUMO electronic states of single molecules between electrodes, but also by the atomic-scale contact conditions. We show that the transitions from tunneling to ballistic regimes affect the I– V characteristics significantly.