Phase transitions in partial summation methods: Results from the three-dimensional Hubbard model

Abstract

A minimal model of a correlation-driven phase transition is the half-filled Hubbard model in three dimensions, for which numerically exact solutions are available. The authors compare exact results to results obtained from a range of diagrammatic perturbation theories, generalizable to real materials problems. They demonstrate that quantum embedding leads to an efficient elimination of finite-size effects. However, perturbative methods do not provide an accurate description of the phase transition even in the regime of weak-to-intermediate coupling.

Topics & Concepts