Density functionals derived from Feynman diagrams

TL;DR

This paper introduces a new method for constructing stationary density functionals directly from selected Feynman diagrams, applicable to fermions with Coulomb interactions and nucleons with mesons, bypassing the need for Kohn-Sham orbitals.

Contribution

A novel approach to derive density functionals from Feynman diagrams without using Legendre transform inversion, simplifying the functional construction process.

Findings

Constructed stationary density functionals from Feynman diagrams for fermions and nucleons.

Eliminated the need for Kohn-Sham orbitals in the functional formulation.

Applicable to systems with Coulomb interactions and meson interactions.

Abstract

We construct a stationary density functional for the partition function from a chosen set of one (boson) line irreducible Feynman diagrams. The construction does not proceed by the inversion of a Legendre transform. It is formulated for fermions with Coulomb interactions, in which case a stationary functional of the particle density is contructed, as well as for nucleons interacting with mesons, which involves a stationary functional of several densities. The use of Kohn-Sham orbits is shown to be an unnecessary complication.