Spectral properties of high-Tc cuprates via a cluster-perturbation approach

Angular-resolved photoemission data on half-filled doped cuprate materials are compared with an exact-diagonalization analysis of the three-band Hubbard model, which is extended to the infinite lattice by means of a perturbation in the intercluster hopping (cluster perturbation theory). A study of the band dispersion and spectral weight of the insulating cuprate Sr2CuO2Cl2 allows us to fix a consistent parameter set, which turns out to be appropriate at finite dopings as well. In the overdoped regime, our results for the spectral weight and for the Fermi surface give a good description of the experimental data on Bi2Sr2CaCu2O8+delta. In particular, the Fermi surface is hole-like and centered around k = (pi,pi). Finally, we introduce a hopping between two layers and address the issue of bilayer splitting.