Slave rotor approach to dynamically screened Coulomb interactions in solids

TL;DR

This paper introduces a slave rotor-based method within dynamical mean-field theory to analyze dynamically screened Coulomb interactions in solids, improving the understanding and approximation of dynamical impurity problems.

Contribution

It develops a systematic approach using slave rotors to decouple dynamical interactions, enhancing solution schemes for dynamical impurity models in correlated electron systems.

Findings

The scheme accurately reproduces known results.

Comparison shows improved approximation over existing methods.

Optimized Bose factor choice enhances computational efficiency.

Abstract

Recent studies of dynamical screening of the electronic Coulomb interactions in solids have revived interest in lattice models of correlated fermions coupled to bosonic degrees of freedom (Hubbard-Holstein-type models). We propose a dynamical mean-field-based approach to dynamically screened Coulomb interactions. In the effective Anderson-Holstein model, a transformation to slave rotors [S. Florens and A. Georges, Phys. Rev. B 66, 165111 (2002)] is performed to decouple the dynamical part of the interaction. This transformation allows for a systematic derivation and analysis of recently introduced approximate schemes for the solution of dynamical impurity problems, in particular, the Bose factor ansatz within the dynamic atomic limit approximation (DALA) with and without Lang-Firsov correction. More importantly still, it suggests an optimized choice for a Bose factor in the sense of the variational principle of Feynman and Peierls. We demonstrate the accuracy of our scheme and present a comparison to calculations within the DALA.