Valleys in configuration space of Coulomb glasses

We study numerically the effective number of electrons participating in low -energy transitions in Coulomb glasses comparing the results with those of systems with other types of interactions. Through this study we estimate th e number of particles involved in a typical low-energy transition between c onfigurations. This number increases with system size for long-range intera ctions, while it is basically constant for a short-range interaction. Final ly we calculate the density of metastable configurations, i.e. valleys, cla ssified according to their degree of stability.