We have performed semiempirical tight-binding calculations of the electronic structure of YBa2Cu3O7, with d and s orbitals included for all the metal atoms and p and s orbitals for the oxygen. Here we report studies of the following atomic substitutions: Al, Fe, Co, Ni, and Zn replacing Cu; Sr and La replacing Ba; Tl, Pb, and Bi replacing Y; and F and N replacing O. In each case, the modification of the local densities of states, the atomic valences, and the Fermi energy were calculated. 1988 The American Physical Society.
