  We calculate numerically the spectrum of disordered electrons in the lowest
Landau level at filling factor 1/5 using the self-consistent Hartree-Fock
approximation for systems containing up to 400 flux quanta. Special attention
is paid to the correct treatment of the q=0 component of the Coulomb
interaction. For sufficiently strong disorder, the system is an insulator at
this filling factor. We observe numerically a Coulomb gap in the
single-particle density of states (DOS). The DOS agrees quantitatively with the
predictions for classical point charges.
