Vibronic effects on resonant electron conduction through single molecule junctions

The influence of vibrational motion on electron conduction through single molecules bound to metal electrodes is investigated employing first-principles electronic-structure calculations and projection-operator Green's function methods. Considering molecular junctions where a central phenyl ring is coupled via (alkane)thiol-bridges to gold electrodes, it is shown that - depending on the distance between the electronic π-system and the metal - electronic-vibrational coupling may result in pronounced vibrational substructures in the transmittance, a significantly reduced current as well as a quenching of negative differential resistance effects.