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 Sr 2 CuO 2 Cl 2 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 Bi 2 Sr 2 CaCu 2 O 8+(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.