Oxygen-disorder effects on the electronic structure of YBa2Cu3O6+δ

The electronic structure of YBa2Cu3O6+δ is calculated in the framework of the tight-binding Hamiltonian. The effects of the oxygen concentration δ and its spatial ordering in the basal plane are studied by means of the Bethe-lattice method. The local density of states at the various Cu and O sites are calculated as a function of δ and of the degree of oxygen ordering. Special attention is given to the number of holes h in both the ordered and disordered systems for various concentrations. We find that the electronic structure at the CuO2 planes is almost insensitive to the degree of order, in contrast to the local density of states of sites located in the basal plane