Revision of the theory of a uniform electron gas

TL;DR

This paper revises the theory of a uniform electron gas by demonstrating the importance of degeneracy in the unperturbed system, leading to more accurate ground state energy calculations using degenerate perturbation theory.

Contribution

It reveals that the unperturbed uniform electron gas is strongly degenerate and applies degenerate perturbation theory to improve ground state energy estimates.

Findings

Degeneracy significantly affects the ground state energy calculations.

Degenerate perturbation theory yields lower energy values than non-degenerate methods.

Revises the foundational understanding of the electron gas model.

Abstract

The many-body theory of a uniform electron gas was developed at the end of 1950ies. The Coulomb interaction between electrons was considered as a perturbation and the ground state energy was calculated in all orders of the non-degenerate perturbation theory. We show that the ground state of the unperturbed system is actually strongly degenerate and that the degenerate perturbation theory leads to lower values of the ground state energy.