Fast multi-orbital equation of motion impurity solver for dynamical mean field theory

TL;DR

This paper introduces a rapid multi-orbital impurity solver for DMFT based on equations of motion, effectively capturing key phenomena like the Mott transition and quasiparticle peaks, with good agreement to QMC results.

Contribution

It generalizes the EOM impurity solver from single to multi-orbital systems, including inter-orbital hybridizations and Coulomb interactions, providing a faster alternative to existing methods.

Findings

Successfully describes Mott transition and quasiparticle peaks

Shows good agreement with QMC results for two-orbital Hubbard model

Offers a computationally efficient impurity solver for strongly correlated systems

Abstract

We propose a fast multi-orbital impurity solver for the dynamical mean field theory (DMFT). Our DMFT solver is based on the equations of motion (EOM) for local Green's functions and constructed by generalizing from the single-orbital case to the multi-orbital case with inclusion of the inter-orbital hybridizations and applying a mean field approximation to the inter-orbital Coulomb interactions. The two-orbital Hubbard model is studied using this impurity solver within a large range of parameters. The Mott metal-insulator transition and the quasiparticle peak are well described. A comparison of the EOM method with the QMC method is made for the two-orbital Hubbard model and a good agreement is obtained. The developed method hence holds promise as a fast DMFT impurity solver in studies of strongly correlated systems.