Influence of external voltage on electronic transport properties of molecular junctions: the nonlinear transport behaviour

The influence of external voltage on the charge transport properties of benzene-1,4-dithiolate molecular junction has been investigated. Variations of the geometric and electronic structures for the molecule caused by the applied voltage are calculated at ab initio level. Based on the numerical results, we find that the energy shift and expansion coefficients in the end-site of the molecule for the frontier molecular orbitals show nearly linear dependence on voltage in the interested voltage interval. The charge transport properties of the molecular junction are then studied by employing the elastic scattering Green's function method. It is shown that the voltage has an obvious effect on the I - V characteristic of the molecular junction, particularly the shape of the conductance curves. The I - V curves are consistent with the experimental measurement quite well.