Effect of dipole moment on current-voltage characteristics of single molecules

The authors perform empirical calculations of the tunneling current through various small organic molecules sandwiched between gold electrodes by using the Wenzel-Kramers-Brillouin (WKB) approximation. The barrier to tunneling is taken to be the work function of gold and calculated from a first principles electronic structure code. The current-voltage characteristics of these molecules are compared in the context of existing first principles and experimental results. In this model the surface dipole moment, induced by the adsorbed molecule can have a significant effect on the current and hence dipole moments may be an important property for prediction of the conductance characteristics of a molecule.