System-adapted correlation energy density functionals from effective pair interactions

TL;DR

This paper introduces an average-pair-density functional theory that rewrites the ground-state energy as a functional of pair density, enabling the development of system-specific correlation functionals by combining with density functional theory.

Contribution

It proposes a novel average-pair-density functional framework and demonstrates how to create system-adapted correlation energy functionals within density functional theory.

Findings

Applicable to He series and uniform electron gas

Provides a simple approximation for effective electron-electron interactions

Shows potential for system-specific correlation energy functionals

Abstract

We present and discuss some ideas concerning an ``average-pair-density functional theory'', in which the ground-state energy of a many-electron system is rewritten as a functional of the spherically and system-averaged pair density. These ideas are further clarified with simple physical examples. We then show that the proposed formalism can be combined with density functional theory to build system-adapted correlation energy functionals. A simple approximation for the unknown effective electron-electron interaction that enters in this combined approach is described, and results for the He series and for the uniform electron gas are briefly reviewed.