Electronic spectrum and hopping conductivity in highly doped lattice   systems
  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. 
Yuri G. Pogorelov, J. M. B. Lopes dos Santos, J. M. V. P. Lopes