Thermal mean-field theories

TL;DR

This paper compares various ab initio thermal mean-field theories for fermions, analyzing their formalism and numerical performance against the thermal full-configuration-interaction benchmark.

Contribution

It provides a comprehensive comparison of well-established and new thermal mean-field theories at the formalism and numerical levels.

Findings

Fermi-Dirac theory and thermal Hartree-Fock show different accuracy levels.

Modifications of the thermal single-determinant approximation are evaluated.

First-order finite-temperature perturbation theory's performance is assessed.

Abstract

Several closely related ab initio thermal mean-field theories for fermions, both well-established and new ones, are compared with one another at the formalism level and numerically. The theories considered are Fermi-Dirac theory, thermal Hartree-Fock (HF) theory, two modifications of the thermal single-determinant approximation of Kaplan and Argyres, and first-order finite-temperature many-body perturbation theory based on zero-temperature or thermal HF reference. The thermal full-configuration-interaction theory is used as the benchmark.