Multi-Orbital Hubbard Model in Infinite Dimensions: Quantum Monte Carlo Calculation

TL;DR

This paper uses Quantum Monte Carlo to study the orbitally degenerate Hubbard model in infinite dimensions, revealing how orbital degeneracy affects spectra, Mott transition, and resistivity.

Contribution

It provides new insights into the effects of orbital degeneracy and Hund's coupling on the Hubbard model's thermodynamics and spectral properties in infinite dimensions.

Findings

Broader Hubbard bands with increased degeneracy

Narrower Mott gap as degeneracy increases

Quadratic resistivity at low temperatures for two-fold degeneracy

Abstract

Using Quantum Monte Carlo we compute thermodynamics and spectra for the orbitally degenerate Hubbard model in infinite spatial dimensions. With increasing orbital degeneracy we find in the one-particle spectra: broader Hubbard bands (consistent with increased kinetic energy), a narrowing Mott gap, and increasing quasi-particle spectral weight. In opposition, Hund's rule exchange coupling decreases the critical on-site Coulomb energy for the Mott transition. The metallic regime resistivity for two-fold degeneracy is quadratic-in-temperature at low temperatures.