Effects of coupling to vibrational modes on the ac conductance of molecular junctions

TL;DR

This paper theoretically investigates how coupling electrons to vibrational modes in molecular junctions affects their ac conductance, revealing temperature-dependent enhancements or suppressions and additional peak structures observable through tuning tunnel couplings.

Contribution

It introduces a model analyzing vibrational effects on ac conductance in molecular junctions, highlighting vertex correction-induced peak structures and temperature-dependent conductance behavior.

Findings

Vibrational coupling enhances or suppresses conductance depending on chemical potential.

Vertex corrections create observable peak structures in conductance.

Conductance behavior varies significantly with temperature and tunnel coupling tuning.

Abstract

We theoretically examine the effect of the coupling of the transport electrons to a vibrational mode of the molecule on the ac linear-response conductance of molecular junctions. Representing the molecule by a single electronic state, we find that at very low temperatures the frequency-dependent conductance is mainly enhanced (suppressed) by the electron-vibration interaction when the chemical potential is below (above) the energy of that state. The vertex corrections of the electron-vibration interaction induce an additional peak structure in the conductance, which can be observed by tuning the tunnel couplings with the leads.