Doping-dependent quasiparticle band structure in cuprate superconductors

We present an exact diagonalization study of the single-particle spectral function in the so-called t-t{sup {prime}}-t{sup {prime}{prime}}-J model in two dimensions. As a key result, we find that hole doping leads to a major reconstruction of the quasiparticle band structure near ({pi},0): whereas for the undoped system the quasiparticle states near ({pi},0) are deep below the top of the band near ({pi}/2,{pi}/2), hole doping shifts these states up to E{sub F}, resulting in extended flat band regions close to E{sub F} and around ({pi},0). {copyright} {ital 1997} {ital The American Physical Society}