Dynamical Screening in Correlated Electron Materials

TL;DR

This paper introduces an efficient method to incorporate dynamical screening effects of the Hubbard U in correlated electron materials within the dynamical mean field theory, revealing significant impacts on phase boundaries and spectral features.

Contribution

It presents a novel formalism for including frequency-dependent interactions in DMFT, improving the understanding of screening effects in correlated materials.

Findings

Screening shifts the metal-insulator phase boundary.

Spectral functions are altered near the Mott-Hubbard gap edge.

Hubbard bands are not simply separated by the interaction energy.

Abstract

We present an efficient method for incorporating the dynamical effects of the screening of the Hubbard U by electronic degrees of freedom in the solid into the single site dynamical mean field approximation. The formalism is illustrated by model system calculations which capture the essential features of the frequency dependent interactions proposed for Gd, Ni, SrVO_3 and other compounds. Screening leads to shifts in the metal-insulator phase boundary, changes in the spectral function near the Mott-Hubbard gap edge and to a renormalization of the quasiparticle weight. Hubbard bands are generically neither separated by the screened nor the unscreened interaction energy, implying that the common practice of extracting the Hubbard U from the energies of features in photoemission and inverse photoemission spectra requires reexamination.