FIRST ORDER METAL-INSULATOR TRANSITION IN AN ALLOY ANALOGY APPROACH TO THE HUBBARD MODEL

Abstract

The self-consistent coherent potential approximation introduced in Ref. 3 is extended to the hopping part of the Hubbard Hamiltonian in an alloy analogy scheme. There results the renormalization of the unperturbed bandwidth w by the appearance of a spin and potential strength dependent factor Φσ(u), the latter leads — in the magnetically disordered case, at electron densities n not far from 1, for small values of the temperature k B T with respect to w and values of u smaller than those needed to cause the Hubbard splitting — to a first order metal-insulator transition: Φ and the double occupancy probability D undergo a sudden drop. It is also shown that in the approximation proposed the system becomes strongly ferromagnetic in the thermodynamic limit at n = 1 and T = 0 if u is sufficiently large.