Electron-phonon coupling in correlated materials: insights from the Hubbard-Holstein model

TL;DR

This study uses dynamical mean-field theory to analyze how electron-electron correlations suppress electron-phonon interactions in the Hubbard-Holstein model, revealing frequency-dependent effects relevant for quantum materials.

Contribution

It provides new insights into the interplay between electron-electron and electron-phonon interactions in correlated systems using advanced theoretical modeling.

Findings

Electron-phonon interaction is strongly suppressed by electronic correlations.

Electron-electron correlation effects are weakly modified by phonons at Fermi liquid scales.

Phonon-induced modifications are most evident at high frequencies near the electronic bandwidth.

Abstract

Dynamical mean-field theory computations of the electron self energy of the Hubbard-Holstein model as a function of electron-phonon and electron-electron interactions are analyzed to gain insight into the dependence of electron-phonon couplings on correlation strength in quantum materials. We find that the electron-phonon interaction is strongly suppressed by electronic correlations, while electron-electron correlation effects at Fermi liquid scales are only weakly modified by coupling to phonons, with phonon-induced modifications most evident at high frequencies on the order of the electronic bandwidth. Implications for beyond-density functional theories of the electron-phonon interaction are discussed.