Configuration space in electron glasses

We study numerically the low-energy configuration space of electron glasses . We consider systems with Coulomb interactions, short-range interactions a nd no interactions. First, we calculate the integrated density of configura tions as a function of energy. At a given energy, this density is lower for Coulomb glasses than for short-range systems, which in turn is lower than for non-interacting systems. We analyse how the site occupancy Varies with the number of configurations. Through this study we estimate the number of particles involved in a typical low-energy transition between configuration s. This number increases with increasing system size for long-range interac tions, while it is basically constant for a short-range interaction. Finall y we calculate the density of metastable configurations, that is valleys, c lassified according to their degree of stability.