From a local Green function to molecular charge transport

TL;DR

This paper introduces a local-orbital ab initio method to compute Green functions for large systems, enabling detailed analysis of molecular charge transport with correlation effects.

Contribution

It develops a Green function formalism based on exact diagonalization and an incremental self-energy scheme for large heterogeneous systems.

Findings

Applied to ditholbenzene molecular junctions with gold electrodes.

Analyzed the impact of different local correlation contributions.

Demonstrated feasibility of the approach for complex molecular systems.

Abstract

A local-orbital based ab initio approach to obtain the Green function for large heterogeneous systems is developed. First a Green function formalism is introduced based on exact diagonalization. Then the self energy is constructed from an incremental scheme, rendering the procedure feasible, while at the same time physical insight into different local correlation contributions is obtained. Subsequently the Green function is used in the frame of the Landauer theory and the wide band approximation to calculate the electronic transmission coefficient across molecular junctions. The theory is applied to meta- and para-ditholbenzene linked to gold electrodes and various correlation contributions are analyzed.