From local to non-local correlations: the Dual Boson perspective

TL;DR

This paper introduces a dual boson formalism that extends EDMFT to better capture non-local correlations in strongly correlated systems, improving phase boundary predictions efficiently.

Contribution

The paper develops a diagrammatic extension of EDMFT using the dual boson formalism to accurately include non-local correlations without double counting.

Findings

Improved charge order transition phase boundary predictions.

Efficient computational scheme comparable to EDMFT+GW.

Enhanced description of non-local effects in strongly correlated systems.

Abstract

Extended dynamical mean-field theory (EDMFT) is insufficient to describe non-local effects in strongly correlated systems, since corrections to the mean-field solution are generally large. We present an efficient scheme for the construction of diagrammatic extensions of EDMFT that avoids usual double counting problem by using an exact change of variables (the dual boson formalism) to distinguish the correlations included in the mean-field solution and those beyond. With a computational efficiency comparable to EDMFT+GW approach, our scheme significantly improves on the charge order transition phase boundary in the extended Hubbard model.