Oxygen Banding in Cuprate Superconductors

A simple procedure is proposed for modeling the o(2p) bands of cuprate compounds in the limit where the Cu(3d) electrons are localized by correlation effects such as the on-site Coulomb energy u sub d. This scheme, which involves orthogonalization of the linear augmented-plane-wave (LAPW) basis to the Cu(3d) states, has been applied to Ca sub 0.86 Sr sub 0.14 CuO sub 2, the parent compound of the Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O high T sub c superconductors. Tight-binding fits to the LAPW results for Ca sub 0.86 Sr sub 0.14 CuO sub 2 with localized and itinerant Cu(3d) electrons yield O p-p interaction parameters which fit both limits equally well.