  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.
