Advanced multi-orbital impurity solver for dynamical mean field theory based on the equation of motion approach

TL;DR

This paper introduces an improved multi-orbital impurity solver for DMFT using an equation of motion approach, which accurately accounts for inter-orbital interactions and fluctuations, and shows good agreement with established methods.

Contribution

The paper develops a self-consistent multi-orbital impurity solver based on EOM that effectively captures inter-orbital effects in strongly correlated systems.

Findings

Good agreement with quantum Monte Carlo and NRG results

Reveals effects of inter-site and on-site inter-orbital fluctuations

Highlights differences in density of states due to inter-orbital hopping

Abstract

We propose an improved fast multi-orbital impurity solver for the dynamical mean field theory (DMFT) based on equations of motion (EOM) of Green's functions and decoupling scheme. In this scheme the inter-orbital Coulomb interactions are treated fully self-consistently, involving the inter-orbital fluctuations. As an example of the derived multi-orbital impurity solver, the two-orbital Hubbard model is studied for various cases. Comparisons are made between numerical results obtained with our EOM scheme and those obtained with quantum Monte Carlo and numerical renormalization group methods. The comparison substantiates a good agreement, but also reveals a dissimilar behavior in the densities of states (DOS) which is caused by inter-site inter-orbital hopping effects and on-site inter-orbital fluctuation effects, thus corroborating the value of the EOM method for the study of multi-orbital strongly correlated systems.