Efficient atomic self-interaction correction scheme for non-equilibrium quantum transport

TL;DR

This paper introduces a computationally efficient self-interaction correction method for density functional theory that improves the accuracy of electronic transport predictions in metal-molecule-metal junctions, aligning results more closely with experimental data.

Contribution

A fully self-consistent, computationally efficient self-interaction correction scheme implemented in a non-equilibrium transport code, addressing limitations of local functionals in molecular junctions.

Findings

Reduces self-interaction errors in transport calculations.

Improves agreement of low bias current with experiments.

Corrects molecular orbital energies to match ionization potentials.

Abstract

Density functional theory calculations of electronic transport based on local exchange and correlation functionals contain self-interaction errors. These originate from the interaction of an electron with the potential generated by itself and may be significant in metal-molecule-metal junctions due to the localized nature of the molecular orbitals. As a consequence, insulating molecules in weak contact with metallic electrodes erroneously form highly conducting junctions, a failure similar to the inability of local functionals of describing Mott-Hubbard insulators. Here we present a fully self-consistent and still computationally undemanding self-interaction correction scheme that overcomes these limitations. The method is implemented in the Green's function non-equilibrium transport code Smeagol and applied to the prototypical cases of benzene molecules sandwiched between gold electrodes. The self-interaction corrected Kohn-Sham highest occupied molecular orbital now reproduces closely the negative of the molecular ionization potential and is moved away from the gold Fermi energy. This leads to a drastic reduction of the low bias current in much better agreement with experiments.