Accuracy of density functionals for molecular electronics: the Anderson junction

TL;DR

This paper evaluates how well different density functional approximations predict electron transmission in molecular electronics, specifically in an Anderson junction, by analyzing their successes and limitations.

Contribution

It introduces a method to construct the exact exchange-correlation potential using impurity charge susceptibility and assesses various approximation types.

Findings

Exact functional yields precise transmission at zero bias and temperature.

Discontinuous and symmetry-broken functionals show varying accuracy.

Limitations identified in common approximation methods.

Abstract

The exact ground-state exchange-correlation functional of Kohn-Sham density functional theory yields the exact transmission through an Anderson junction at zero bias and temperature. The exact impurity charge susceptibility is used to construct the exact exchange-correlation potential. We analyze the successes and limitations of various types of approximations, including smooth and discontinuous functionals of the occupation, as well as symmetry-broken approaches.