Vibronic effects on resonant electron conduction through single molecule junctions

TL;DR

This paper investigates how vibrational motions in molecules affect electron conduction in single-molecule junctions, revealing that vibrational coupling can alter conductance and suppress certain electronic effects.

Contribution

It provides first-principles calculations showing the impact of vibronic effects on electron transport in molecular junctions with phenyl rings and thiol-bridges.

Findings

Vibrational coupling causes vibrational substructures in transmittance.

Electronic-vibrational interactions can reduce current flow.

Vibrational effects can quench negative differential resistance.

Abstract

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 $\pi$-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.