Is reduced-density-matrix functional theory a suitable vehicle to import explicit correlations into density-functional calculations?

TL;DR

This paper introduces a variational density-matrix functional theory approach that effectively incorporates explicit many-particle correlations into density-functional calculations, avoiding double-counting issues and improving ground state property predictions.

Contribution

It presents a novel variational formalism integrating explicit correlations into DFT, with a local approximation that enhances accuracy over mean-field methods.

Findings

Successfully captures ground state properties of Hubbard chains

Avoids double-counting of correlation effects

Demonstrates improved accuracy over mean-field theories

Abstract

A variational formulation for the calculation of interacting fermion systems based on the density-matrix functional theory is presented. Our formalism provides for a natural integration of explicit many-particle effects into standard density-functional-theory based calculations and it avoids ambiguities of double-counting terms inherent to other approaches. Like the dynamical mean-field theory, we employ a local approximation for explicit correlations. Aiming at the ground state only, trade some of the complexity of Green's function based many-particle methods against efficiency. Using short Hubbard chains as test systems we demonstrate that the method captures ground state properties, such as left-right-correlation, beyond those accessible by mean-field theories.