Impact of Exchange-Correlation Effects on the IV Characteristics of a Molecular Junction

TL;DR

This paper investigates how exchange-correlation effects influence the current-voltage characteristics of molecular junctions using advanced many-body perturbation theory, revealing significant renormalization and lifetime effects that alter transport behavior.

Contribution

It introduces a self-consistent many-body perturbation approach to analyze exchange-correlation effects on molecular junction transport, highlighting phenomena not captured by standard DFT methods.

Findings

Bias-induced peaks in dI/dV due to HOMO-LUMO interplay

Self-interaction errors suppress certain effects

Dynamic correlations significantly renormalize energy levels and reduce QP lifetimes

Abstract

The role of exchange-correlation effects in non-equilibrium quantum transport through molecular junctions is assessed by analyzing the IV curve of a generic two-level model using self-consistent many-body perturbation theory (second Born and GW approximations) on the Keldysh contour. For weak molecule-lead coupling we identify a mechanism which can lead to anomalously strong peaks in the dI/dV due to a bias-induced interplay between the position of the HOMO and LUMO levels. The effect is suppressed by self-interaction errors and is therefore unlikely to be observed in standard transport calculations based on density functional theory. Inclusion of dynamic correlations lead to substantial renormalization of the energy levels. In particular, we find a strong enhancement of quasi-particle (QP) scattering at finite bias which reduces the QP lifetimes significantly with a large impact on the IV curve.