T>0 ensemble state density functional theory revisited

TL;DR

This paper revisits the theoretical foundations of finite-temperature density functional theory within a Kohn-Sham framework, providing a clearer, more robust derivation that addresses previous open issues and is relevant for complex phenomena like magnetism.

Contribution

It offers a simplified, logically consistent foundation for finite-temperature density functional theory based on Mermin's grand canonical approach, improving upon traditional derivations.

Findings

Provides a more satisfactory derivation of finite-temperature DFT

Addresses open issues in the theoretical foundation

Applicable to symmetry-breaking phenomena like magnetism

Abstract

A logical foundation of equilibrium state density functional theory in a Kohn-Sham type formulation is presented on the basis of Mermin's treatment of the grand canonical state. it is simpler and more satisfactory compared to the usual derivation of ground state theory, and free of remaining open points of the latter. It may in particular be relevant with respect to cases of spontaneous symmetry breaking like non-collinear magnetism and orbital order.