Doping dependence of hole distribution in CuO2 planes of high-Tc superconductors: Local ansatz versus exact results

The hole distribution within a CuO2 plane, a common structural element of high-temperature superconductors, is investigated as a function of doping by holes. The correlated ground state of a three-band Hubbard model is found by making use of a local ansatz which includes local correlations between holes. It is found that doped holes have ∼70% oxygen character for the parameters determined from the local-density approximation, in agreement with experimental observations, while hole droplets on oxygen orbitals are formed for large copper-oxygen Coulomb repulsion, Udp. All our results agree with those obtained from finite-cluster diagonalization