Abstract
α' − NaV2O5 is classified as a dimerized layered system with strongly interacting d-electrons of vanadium ions. The derived band gaps, energy dispersion relations and density of electronic states are in good agreement with available experimental and theoretical data. The correlated band gap provides the insulating state of the high-temperature phase whereas the state, earlier misinterpreted as the spin-Peierls state, is governed, in fact, by the opening of the Coulomb gap.