Using the two-band model introduced by Mota and Coutinho-Filho, the metal-nonmetal transition is investigated by Hamiltonian approximation model which takes into account the hybridization of the bands, not included in the original model. The Green's function technique is used to obtain the hybrid bands inthe Hartree-Fock approximation. Investigating the phenomenon of metal-nonmetal transition, in general, increasing the intra-atomic interaction the tendency of the systems towards nonmetalic behavior increases. But, differently from previous results, for strong hybridization and small intra-atomic interaction, where the Hartree-fock approximation is valid, the opposite is observed. this may help to understand the difficult observing pressure-induced nonmetal-metal transitions in magnetic systems
