On the Accuracy of the Noninteracting Electron Approximation for Vibrationally Coupled Electron Transport

TL;DR

This paper investigates the validity of the noninteracting electron approximation in vibrationally coupled electron transport, revealing its limitations in accurately predicting long-term dynamics in molecular junctions.

Contribution

It introduces an analysis of the approximation's accuracy using ML-MCTDH for nuclear dynamics while maintaining a noninteracting electronic model.

Findings

Approximation is reasonable for short-term dynamics.

Fails to predict correct long-term behavior under certain conditions.

Highlights importance of electron-electron correlation effects.

Abstract

The accuracy of the noninteracting electron approximation is examined for a model of vibrationally coupled electron transport in single molecule junction. In the absence of electronic-vibrational coupling, steady state transport in this model is described exactly by Landauer theory. Including coupling, both electronic-vibrational and vibrationally induced electron-electron correlation effects may contribute to the real time quantum dynamics. Using the multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) theory to describe nuclear dynamics exactly while maintaining the noninteracting electron approximation for the electronic dynamics, the correlation effects are analyzed in different physical regimes. It is shown that although the noninteracting electron approximation may be reasonable for describing short time dynamics, it does not give the correct long time limit for certain initial conditions.