By the use of the crystal cluster method, it becomes possible (1) to obtain good agreement with band calculations of charge distribution, practically beginning with minimal clusters and, (2) to reproduce well the energy position of the VB; however (3), in order to analyze the detailed structure of density of states of the VB for the NaCl crystal, it is necessary to account for five or six spheres of the environment in order to provide convergence of this most sensitive characteristic. In this case, (4) the calculated model density of states of the atom-representatives of the bases converges with that obtained in the band calculation. In calculations of states of the CB, replacement of the operator of projection on the space of Wannier functions by an external localizing potential leads to a considerable distortion of the spectrum. The states obtained in this region (5) are determined by this external potential; and (6) they should be interpreted as lower states of the CB. (7) The use of a correction for the localizing potential improves the agreement with respect to the width of the optical gap in the series of calculations.