A new mechanism is proposed to explain the origin of negative differential resistance (NDR) in a strongly coupled single molecule-metal junction. A first-principles quantum transport calculation in a Fe-terpyridine linker molecule sandwiched between a pair of gold electrodes is presented. Upon increasing applied bias, it is found that a new phase in the broken symmetry wavefunction of the molecule emerges from the mixing of occupied and unoccupied molecular orbital. As a consequence, a non-linear change in the coupling between molecule and lead is evolved resulting to NDR. This model can be used to explain NDR in other class of metal-molecule junction device.
@article{arxiv.0803.3342,
title = {Origin of negative differential resistance in a strongly coupled single molecule-metal junction device},
author = {Ranjit Pati and Mike McClain and Anirban Bandyopadhyay},
journal= {arXiv preprint arXiv:0803.3342},
year = {2009}
}