Bethe-Peierls-Weiss approximation for the two- and three-dimensional Coulomb glass: zero-temperature and finite-temperature results

Abstract

The Bethe-Peierls-Weiss approximation is applied to the Coulomb glass Hamiltonian in two and three dimensions. The single-particle density of states (DOS) at zero temperature is calculated analytically; it has a soft Coulomb gap at the Fermi energy. The authors rederive the self-consistent equation of Efros (1975), but not the altered version given by Baranovskii, Efros, Gelmont and Shklovskii (1979). The DOS is independent of the mean occupation number of the sites. These results are compared with numerical simulations of the model. The influence of finite temperatures on the DOS is discussed qualitatively. The Coulomb gap fills with increasing temperature T. For kT smaller than the gap width the DOS at the Fermi energy is proportional to kTD-1.