Monte Carlo simulations of the electron glass

We have performed Monte Carlo simulations on a classical model of disordered insulators with Coulomb interactions between electrons, i.e., N sites randomly distributed in space, and N/2 electrons with 1/r interactions between them. The electrons can move via variable-range hopping. Autocorrelation functions 〈q(t)q(0)${〉}_T$ at different temperatures have been calculated. From the shape of the autocorrelation function, we find a broad distribution of relaxation times and no finite transition temperature for the two-dimensional model. The equal-time density-density correlation function is also calculated as a function of momentum, and the screening properties are shown to cross over from metallic screening at high temperatures to dielectric screening due to dipole pairs at low temperature. This crossover is indicative of a glassy behavior. A comparison with some recent experiments is also made.