Filling dependence of the Mott transition in the degenerate Hubbard model

TL;DR

This paper investigates how doping levels influence the Mott transition in a generalized Hubbard model for doped Fullerenes, revealing that the transition occurs at smaller Coulomb interactions away from half-filling.

Contribution

It provides a detailed analysis of the doping dependence of the Mott transition using fixed-node diffusion Monte Carlo and introduces a simple model for this dependence.

Findings

Mott transition occurs at smaller U away from half-filling

Energy gap E_g is used as the transition criterion

Doping shifts the critical U for the Mott transition

Abstract

Describing the doped Fullerenes using a generalized Hubbard model, we study the Mott transition for different integer fillings of the t_1u band. We use the opening of the energy-gap E_g as a criterion for the transition. E_g is calculated as a function of the on-site Coulomb interaction U using fixed-node diffusion Monte Carlo. We find that for systems with doping away from half-filling the Mott transitions occurs at smaller U than for the half-filled system. We give a simple model for the doping dependence of the Mott transition.