G. Benenti et al., Compressibility crossover and quantum opening of a gap for two-dimensionaldisordered clusters with Coulomb repulsion, EUR PHY J B, 17(3), 2000, pp. 515-521
Using Hartree-Fock orbitals with residual Coulomb repulsion, we study spinl
ess fermions in a two-dimensional random potential. When we increase the sy
stem size L at fixed particle density, the size dependence of the average i
nverse compressibility exhibits a smooth crossover from a 1/L-2 towards a 1
/L decay when the Coulomb energy to Fermi energy ratio r(s) increases from
0 to 3. In contrast, the distribution of the first energy excitation displa
ys a sharp Poisson-Wigner-like transition at r(s) approximate to 1.