Nonequilibrium excitations of molecular vibrons

TL;DR

This paper investigates how molecular vibrations behave under nonequilibrium conditions in a current-carrying molecular junction, using Green functions and self-consistent methods to reveal vibron emission, instability, and resonance effects.

Contribution

It introduces a self-consistent Green function approach to analyze nonequilibrium vibrons in molecular junctions, highlighting the role of electron-vibron resonance and instability phenomena.

Findings

Vibron emission and instability can occur under nonequilibrium conditions.

Electron-vibron resonance significantly influences vibrational dynamics.

Self-consistent solutions reveal the importance of vibrational effects in molecular transport.

Abstract

We consider the nonequilibrium quantum vibrations of a molecule clamped between two macroscopic leads in a current-carrying state at finite voltages. Our approach is based on the nonequilibrium Green function technique and the self-consistent Born approximation. Kinetic equations for the average populations of electrons and vibrons are formulated in the weak electron-vibron coupling case and self-consistent solutions are obtained. The effects of vibron emission and vibronic instability are demonstrated using few-orbital models. The importance of the electron-vibron resonance is shown.