Quantum Coulomb glass - Hartree-Fock approximation versus exact diagonalization

TL;DR

This paper compares Hartree-Fock approximation and exact diagonalization methods in studying disordered interacting electrons in the quantum Coulomb glass model, highlighting the approximation's accuracy near the Fermi level.

Contribution

It evaluates the validity of the Hartree-Fock method against exact diagonalization for the quantum Coulomb glass, focusing on density of states and localization properties.

Findings

Hartree-Fock accurately predicts the density of states across energies.

Near the Fermi level, Hartree-Fock correctly captures localization properties.

The study discusses implications for electron localization in disordered systems.

Abstract

We investigate the behavior of disordered interacting electrons in the insulating regime. Our study is based on the quantum Coulomb glass model which is obtained from the classical Coulomb glass by adding hopping matrix elements between neighboring sites. We use two different numerical methods, viz. a Hartree-Fock approximation and an exact diagonalization and compare the results for the tunneling density of states and the localization properties in order to determine the range of validity of the Hartree-Fock method. We find that the Hartree-Fock method gives a good approximation for the density of states for all energies but represents the localization properties correctly close to the Fermi level only. Some consequences for the localization of disordered interacting electrons are discussed.