CNDO studies of Y-Ba-Cu-O superconductors IV. The oxygen content effect

The dependence of the electronic structure of superconducting YBa₂Cu₃O _y , is investigated using a quasi-relativistic CNDO/1 molecular orbital method. Electronic structures of model clusters Ba₈Cu₃O _n ] ^q with total chargesq=23–2n forn=11 to 14 in various Cu(1) coordination geometries are compared. The increasing oxygen content causes the electron density transfer from the central Cu(1)O(1,5) _x area to the lateral Cu(2)O(3,4)₂ sheets. The isomerization effects are important for the structures withn=12.