  We present a novel ab initio non-equilibrium approach to calculate the
current across a molecular junction. The method rests on a wave function based
full ab initio description of the central region of the junction combined with
a tight binding approximation for the electrodes in the frame of the Keldysh
Green's function formalism. Our procedure is demonstrated for a dithiolethine
molecule between silver electrodes. The main conducting channel is identified
and the full current-voltage characteristic is calculated.
