Many-body correlations and coupling in benzene-dithiol junctions

TL;DR

This study investigates how many-body perturbation theory affects the calculated conductance of benzene-dithiol junctions, showing that the impact varies with metal-molecule coupling strength and improves agreement with experiments in weakly coupled cases.

Contribution

It demonstrates the dependence of many-body corrections on coupling strength in BDT junctions, refining theoretical conductance predictions beyond standard DFT methods.

Findings

Many-body corrections reduce conductance overestimation in weakly coupled junctions.

In strongly coupled junctions, standard DFT remains sufficiently accurate.

Corrections improve agreement with experimental conductance measurements.

Abstract

Most theoretical studies of nanoscale transport in molecular junctions rely on the combination of the Landauer formalism with Kohn-Sham density functional theory (DFT) using standard local and semilocal functionals to approximate exchange and correlation effects. In many cases, the resulting conductance is overestimated with respect to experiments. Recent works have demonstrated that this discrepancy may be reduced when including many-body corrections on top of DFT. Here we study benzene-dithiol (BDT) gold junctions and analyze the effect of many-body perturbation theory (MBPT) on the calculation of the conductance with respect to different bonding geometries. We find that the many-body corrections to the conductance strongly depend on the metal-molecule coupling strength. In the BDT junction with the lowest coupling, many-body corrections reduce the overestimation on the conductance to a factor two, improving the agreement with experiments. In contrast, in the strongest coupling cases, many-body corrections on the conductance are found to be sensibly smaller and standard DFT reveals a valid approach.