Broken Symmetry in Density-Functional Theory: Analysis and Cure

TL;DR

This paper analyzes the causes of broken symmetry in density-functional theory solutions for quantum dots and proposes a systematic multi-configuration approach to restore symmetry, improving the accuracy of DFT predictions.

Contribution

It introduces a general scheme to incorporate multiple configurations into DFT, effectively curing symmetry breaking issues in mean-field solutions.

Findings

DFT symmetry breaking stems from single-configuration wave functions.

The proposed multi-configuration scheme restores symmetry in DFT.

The method is easily applicable to various density-functional approaches.

Abstract

We present a detailed analysis of the broken-symmetry mean-field solutions using a four-electron rectangular quantum dot as a model system. Comparisons of the density-functional theory predictions with the exact ones show that the symmetry breaking results from the single-configuration wave function used in the mean-field approach. As a general cure we present a scheme that systematically incorporates several configurations into the density-functional theory and restores the symmetry. This cure is easily applicable to any density-functional approach.