Dynamical screening effects in correlated materials: plasmon satellites and spectral weight transfers from a Green's function ansatz to extended dynamical mean field theory

TL;DR

This paper introduces a Green's function ansatz for modeling dynamical screening effects in correlated materials, enabling efficient analysis of plasmon satellites and spectral weight transfers within extended dynamical mean field theory.

Contribution

The authors develop a Green's function factorization method for retarded interactions, simplifying the treatment of dynamical screening in correlated electron systems and benchmarking it against exact solutions.

Findings

Accurately reproduces spectral features in Anderson-Holstein model

Captures effective mass renormalization in SrVO3

Provides a general framework for satellites in correlated materials

Abstract

Dynamical screening of the Coulomb interactions in correlated electron systems results in a low-energy effective problem with a dynamical Hubbard interaction U(omega). We propose a Green's function ansatz for the Anderson impurity problem with retarded interactions, in which the Green's function factorizes into a contribution stemming from an effective static-U problem and a bosonic high-energy part introducing collective plasmon excitations. Our approach relies on the scale separation of the low-energy properties, related to the instantaneous static U, from the intermediate to high energy features originating from the retarded part of the interaction. We argue that for correlated materials where retarded interactions arise from downfolding higher-energy degrees of freedom, the characteristic frequencies are typically in the antiadiabatic regime. In this case, accurate approximations to the bosonic factor are relatively easy to construct, with the most simple being the boson factor of the dynamical atomic limit problem. We benchmark the quality of our method against numerically exact continuous time quantum Monte Carlo results for the Anderson-Holstein model both, at half- and quarter-filling. Furthermore we study the Mott transition within the Hubbard-Holstein model within extended dynamical mean field theory. Finally, we apply our technique to a realistic three-band Hamiltonian for SrVO3. We show that our approach reproduces both, the effective mass renormalization and the position of the lower Hubbard band by means of a dynamically screened U, previously determined ab initio within the constrained random phase approximation. Our approach could also be used within schemes beyond dynamical mean field theory, opening a quite general way of describing satellites and plasmon excitations in correlated materials.