Many-Body Approximation Scheme Beyond GW

TL;DR

This paper combines EDMFT and GWA to improve many-body approximations, demonstrating that using EDMFT for local self-energies as input to GWA yields the most accurate results compared to exact QMC solutions.

Contribution

It introduces a hybrid approach combining EDMFT and GWA, analyzing different self-consistency levels and identifying the most effective scheme for many-body calculations.

Findings

Using EDMFT for local self-energies improves accuracy

The combined method outperforms other self-consistency schemes

Results closely match exact QMC solutions

Abstract

We explore the combination of the extended dynamical mean field theory (EDMFT) with the GW approximation (GWA); the former sums the local contributions to the self-energies to infinite order in closed form and the latter handles the non-local ones to lowest order. We investigate the different levels of self-consistency that can be implemented within this method by comparing to the exact QMC solution of a finite-size model Hamiltonian. We find that using the EDMFT solution for the local self-energies as input to the GWA for the non-local self-energies gives the best result.