Molecular transport calculations with Wannier functions

TL;DR

This paper introduces a computational scheme combining Green's function formalism with density functional theory and Wannier functions to efficiently calculate electron transport in atomic-scale contacts, providing detailed analysis of molecular conductance.

Contribution

The paper presents a novel method that integrates Green's functions, DFT, and Wannier functions for accurate and efficient electron transport calculations at the atomic scale.

Findings

Successfully applied to hydrogen in Pt wire and BDT between Au surfaces

Transmission near Fermi level explained by two molecular orbitals

Method offers detailed chemical insights into transport mechanisms

Abstract

We present a scheme for calculating coherent electron transport in atomic-scale contacts. The method combines a formally exact Green's function formalism with a mean-field description of the electronic structure based on the Kohn-Sham scheme of density functional theory. We use an accurate plane-wave electronic structure method to calculate the eigenstates which are subsequently transformed into a set of localized Wannier functions (WFs). The WFs provide a highly efficient basis set which at the same time is well suited for analysis due to the chemical information contained in the WFs. The method is applied to a hydrogen molecule in an infinite Pt wire and a benzene-dithiol (BDT) molecule between Au(111) surfaces. We show that the transmission function of BDT in a wide energy window around the Fermi level can be completely accounted for by only two molecular orbitals.