Local-field effects in current transport through molecular electronic devices: Current density profiles and local non-equilibrium electron distributions

We analyze non-equilibrium current transport in molecular electronic devices, using as an example devices formed by two terphenyl dithiol molecules attached to gold electrodes. Using a first-principles based self-consistent matrix Green's function method, we show that the spatially resolved current density profiles and local electrochemical potential drops provide valuable information regarding the local field effect on molecular transport, which depend on the internal structure of the molecules and cannot be obtained from measuring the current- and conductance-voltage characteristics alone.