Plasmons in strongly correlated systems: spectral weight transfer and renormalized dispersion

TL;DR

This paper investigates plasmon behavior in a strongly correlated two-dimensional Hubbard model, revealing spectral weight transfer and dispersion renormalization due to electron interactions, beyond standard approximations.

Contribution

It introduces a self-consistent extended dynamical mean-field theory with vertex corrections to accurately describe plasmons in correlated systems.

Findings

Plasmon spectra differ significantly from RPA predictions.

Spectral weight transfer observed in plasmon spectra.

Dispersion shows enhanced deviation from √q behavior.

Abstract

We study the charge-density dynamics within the two-dimensional extended Hubbard model in the presence of long-range Coulomb interaction across the metal-insulator transition point. To take into account strong correlations we start from self-consistent extended dynamical mean-field theory and include non-local dynamical vertex corrections through a ladder approximation to the polarization operator. This is necessary to fulfill charge conservation and to describe plasmons in the correlated state. The calculated plasmon spectra are qualitatively different from those in the random-phase approximation: they exhibit a spectral density transfer and a renormalized dispersion with enhanced deviation from the canonical $\sqrt{q}$-behavior. Both features are reminiscent of interaction induced changes found in single-electron spectra of strongly correlated systems.