Low-temperature specific heat of the Coulomb glass: Role of correlations

An algorithm for the determination of an almost complete set of low-lying system states of an Ising glass sample of up to roughly 500 sites is presented. The method is applied to the investigation of the specific heat of the Coulomb glass. The importance of correlations and the increase of an associated correlation length with decreasing temperature are demonstrated. The studies are extended to temperatures considerably lower than in recent works, which used the Metropolis algorithm. As T→0, the specific heat vanishes superlinearly. At low T, it is considerably larger than its estimate from the often used approximation of independent one-electron hops. © 1996 The American Physical Society.