Mott-Hubbard transition in the N-orbital Hubbard model

The Mort-Hubbard insulator-metal transition (MHT) is studied for the N-orbital symmetrical Hubbard model with diagonal (t(1)) and non-diagonal(t(2)) hopping matrix elements. In the paramagnetic state (PM) For an n = 1 filling the non-diagonal hopping gives rise to two wide Hubbard sub-bands with small spectral weight of the order of similar to 1/N and 2N - 2 narrow sub-bands with a large weight similar to (1 - 1/N). No orbital polarization arises in this solution. In some directions in the (t(1), t(2))-plane the insulating energy gap in the density of stares is closed in the vicinity of a critical Hubbard repulsion of U-c similar to z(t(1) + (N - 1)t(2)) (z-coordination number), whereas the narrow bands in this region of parameters still correspond to a deeply correlated phase (with bandwidth z(t(1) - t(2))). (C) 2000 Elsevier Science B.V. All rights reserved.