Numerical study of relaxation in electron glasses

We perform a numerical simulation of energy relaxation in three-dimensional electron glasses in the strongly localized regime at finite temperatures. We consider systems with no interactions, with long-range Coulomb interacti ons, and with short-range interactions, obtaining a power-law relaxation wi th an exponent of 0.15, which is independent of the parameters of the probl em and of the type of interaction. At very long times, we always find an ex ponential regime whose characteristic time strongly depends on temperature, system size, interaction type, and localization radius. We extrapolate the longest relaxation time to macroscopic sizes and, for interacting samples, obtain values much larger than the measuring time. We finally study the nu mber of electrons participating in the relaxation processes of very low-ene rgy configurations.