Single molecular NDR: A first principles study

The demonstration of single molecule switch with a negative differential resistance (NDR) feature has drawn considerable attention in recent years. The NDR feature is described by a steady increase followed by a decrease in current with the increase in applied bias. Here we report a single molecular NDR in a strongly coupled metal-molecule junction, with peak to valley ratio (PVR) of 2.7 at both positive and negative bias. The bias dependent screening effect is explicitly included in our calculation through a rigorous self-consistent many body approach. The non equilibrium Green function approach is used to calculate the quantum transport. The origin of high PVR will be discussed.