Combination of many-body and density-functional theories

TL;DR

This paper introduces a new framework combining many-body perturbation theory with density-functional concepts, aiming to improve electronic structure calculations by using universal functionals of the Hartree-Fock density.

Contribution

It proposes a novel approach that modifies the reference Hamiltonian with non-local potentials based on density functionals, potentially overcoming limitations of existing density-functional and wavefunction methods.

Findings

Framework justifies the existence of universal functionals for correlation energy

Potential to improve accuracy over traditional density-functional methods

Offers a pathway to better electronic structure models

Abstract

A framework for developing new approximate electronic structure methods is presented, in which the correlation energy of a many-electron system in the ground state is computed as in the single-reference second-order many-body perturbation theory but with the reference one-body Hamiltonian modified by additional (generally non-local) potentials which are universal functionals of the Hartree-Fock density. The existence of such functionals that reproduce the exact correlation energy justifies the search for approximate models which may overcome some important deficiencies of the traditional density-functional methods and also perform better than the usual low-order wavefunction methods.