Strong correlation in Kohn-Sham density functional theory

TL;DR

This paper introduces a new non-local density functional based on the strong-interaction limit of the Hohenberg-Kohn energy, improving the description of strong electron correlation in Kohn-Sham density functional theory.

Contribution

It proposes a highly non-local density functional derived from the strong-interaction limit, enabling better modeling of strong correlation effects in Kohn-Sham calculations.

Findings

Captures essential features of strong correlation in quasi-one-dimensional systems.

Outperforms existing approximations in describing strongly correlated electrons.

Functional derivative is straightforward to construct, facilitating practical implementation.

Abstract

We use the exact strong-interaction limit of the Hohenberg-Kohn energy density functional to approximate the exchange-correlation energy of the restricted Kohn-Sham scheme. Our approximation corresponds to a highly non-local density functional whose functional derivative can be easily constructed, thus transforming exactly, in a physically transparent way, an important part of the electron-electron interaction into an effective local one-body potential. We test our approach on quasi-one-dimensional systems, showing that it captures essential features of strong correlation that restricted Kohn-Sham calculations using the currently available approximations cannot describe.