Wannier functions and Mott localization in the antiferromagnetic phase of high-Tc Cu-oxides

The occurrence of Mott localization in the antiferromagnetic (AF) phase of high-Tc Cu-oxides is analysed within a two-band Hubbard model. A phase diagram giving the degree of localization as a function of the parameters of the model is determined using the Wannier functions relative to the AF Hartree-Fock ground state. It is shown that the degree of localization depends strongly on the value of the charge-transfer gap Δ, and that both situations of strong localization and itinerant magnetism are consistent with an exchange integral J ∼ 0.12 eV and with the range of experimental values reported for Δ. Optical data and measurements of the ordered moment are also discussed within this model, giving some evidence in favour of the strong localization regime