On the location of pπ holes in a high-TC YBa2Cu3O7 superconductor

The electronic structure of YBa2Cu3O7 with a perfect lattice structure, and with one and two lattice defects at O(2), are investigated using cluster approximations. The clusters employed are (Cu4O2)(O4Ba)(Cu4O4)Y and its derivatives, embedded in the ionic cage. Results strongly suggest that the lattice defect(s) at O(1) bring(s) the electron hole(s) to the CuO2 plane.