Hybridization expansion impurity solver: General formulation and application to Kondo lattice and two-orbital models

TL;DR

This paper presents a reformulated hybridization expansion impurity solver applicable to various quantum impurity models, demonstrating its effectiveness in studying Kondo lattice and two-orbital systems at low temperatures and strong couplings.

Contribution

It introduces a general formulation of the hybridization expansion impurity solver that includes spin exchange and pair hopping, broadening its applicability.

Findings

Handles low temperatures and strong couplings without sign problem

Successfully applied to Kondo lattice and two-orbital models

Demonstrates versatility in quantum impurity model simulations

Abstract

A recently developed continuous time solver based on an expansion in hybridization about an exactly solved local limit is reformulated in a manner appropriate for general classes of quantum impurity models including spin exchange and pair hopping terms. The utility of the approach is demonstrated via applications to the dynamical mean field theory of the Kondo lattice and two-orbital models. The algorithm can handle low temperatures and strong couplings without encountering a sign problem.