Non-equilibrium inelastic electronic transport: Polarization effects and vertex corrections to the self-consistent Born approximation

TL;DR

This paper investigates how electron-vibron interactions influence inelastic transport in single-molecule junctions, highlighting the role of vertex corrections and second-order diagrams in modifying conductance features.

Contribution

It introduces a detailed analysis of second-order diagrams, including vertex corrections, on inelastic transport, expanding understanding of their effects across parameter space.

Findings

Vertex correction (DX diagram) renormalizes electron-vibron coupling.

Dressed-phonon (DPH) diagram influences inelastic resonant features.

Second-order diagrams can be approximated for complex systems.

Abstract

We study the effect of electron-vibron interactions on the inelastic transport properties of single-molecule nanojunctions. We use the non-equilibrium Green's functions technique and a model Hamiltonian to calculate the effects of second-order diagrams (double-exchange DX and dressed-phonon DPH diagrams) on the electron-vibration interaction and consider their effects across the full range of parameter space. The DX diagram, corresponding to a vertex correction, introduces an effective dynamical renormalization of the electron-vibron coupling in both the purely inelastic and the inelastic-resonant features of the IETS. The purely inelastic features correspond to an applied bias around the energy of a vibron, while the inelastic-resonant features correspond to peaks (resonance) in the conductance. The DPH diagram affects only the inelastic resonant features. We also discuss the circumstances in which the second-order diagrams may be approximated in the study of more complex model systems.