  A model of strongly disordered lattice system with long-range Coulomb
interactions between localized charge carriers has been considered. The total
electronic energy is characterized by the presence of multiple metastable
minima (including the true ground state), and different types of excitation
spectra over these minima. A numeric procedure, accounting for all many-body
correlations in finite size samples, confirms the existence of Coulomb gap in
the single-particle spectrum and also provides corrections to the known
mean-field theory results, as asymmetry of the gap at non-half-filling,
vanishing density of low energy pair excitations, modified temperature exponent
for hopping conductivity.
