Two-site dynamical mean field theory for the dynamic Hubbard model

TL;DR

This paper applies two-site dynamical mean field theory to the Dynamic Hubbard model at zero temperature, revealing enhanced Mott gap formation and electron-hole asymmetry due to orbital relaxation effects.

Contribution

It introduces a novel application of two-site dynamical mean field theory to the Dynamic Hubbard model, highlighting effects of orbital relaxation and finite boson frequency.

Findings

Enhanced Mott gap at finite boson frequency

Lack of electron-hole symmetry in spectral properties

Distinct behavior from conventional Hubbard models

Abstract

At zero temperature, two-site dynamical mean field theory is applied to the Dynamic Hubbard model. The Dynamic Hubbard model describes the orbital relaxation that occurs when two electrons occupy the same site, by using a two-level boson field at each site. At finite boson frequency, the appearance of a Mott gap is found to be enhanced even though it shows a metallic phase with the same bare on-site interaction $U$ in the conventional Hubbard model. The lack of electron-hole symmetry is highlighted through the quasi-particle weight and the single particle density of states at different fillings, which qualitatively differentiates the dynamic Hubbard model from other conventional Hubbard-like models.