Temperature-induced metal-insulator transition in a narrow-band model with non-equivalent Hubbard subbands at half-filling

In the present paper the temperature-induced metal-insulator transition is studied in a generalized Hubbard model with correlated hopping using recently obtained expression for energy gap. The dependence of energy gap on concentration of doubly occupancy leads to increasing energy gap width with increase of temperature. Thus narrow-band system can undergo transition from a metallic state to an insulating state with the increase of temperature. For some values of intra-atomic Coulomb repulsion U and w0 (w0 is halfbandwidth without taking into account of correlated hopping of electrons) we find the values of temperature when narrow-band material undergoes transition from a metallic state to an insulating state. We show that at given U/w0 metal-insulator transition in model with non-equivalent Hubbard sub-bands can occur at smaller temperature than in the Hubbard model. It testifies on the fact that taking into account of correlated hopping is important for a consideration of metal-insulator transition problem. The obtained results are applied to the interpretation of the experimental data.