Finite-Temperature Gutzwiller Approximation from Time-Dependent Variational Principle

TL;DR

This paper introduces a finite-temperature Gutzwiller approximation derived from the Dirac-Frenkel variational principle, offering improved accuracy over previous methods and aligning well with dynamical mean field theory results.

Contribution

The authors extend the Gutzwiller approximation to finite temperatures without relying on entropy inequalities, enhancing accuracy and applicability.

Findings

Accurately models the Hubbard model at finite temperatures.

Shows good quantitative agreement with dynamical mean field theory.

Applicable to first-principles calculations.

Abstract

We develop an extension of the Gutzwiller approximation to finite temperatures based on the Dirac-Frenkel variational principle. Our method does not rely on any entropy inequality, and is substantially more accurate than the approaches proposed in previous works. We apply our theory to the single-band Hubbard model at different fillings, and show that our results compare quantitatively well with dynamical mean field theory in the metallic phase. We discuss potential applications of our technique within the framework of first principle calculations.