Calculations of the electronic structure of La/sub 2-//sub x/Ba/sub x/CuO/sub 4-//sub y/ by the coherent-potential approximation

We present the first calculations of the electronic structure of the high-temperature superconductors in the disordered phase using the tight-binding coherent-potential approximation. These calculations are used to assess the influence of increasing oxygen vacancies when La is alloyed with M ( = Sr or Ba) in the system La/sub 2-//sub x/M/sub x/CuO/sub 4-//sub y/. Contrary to simple doping arguments, it is found that deoxygenation does not raise the Fermi level (E/sub F/). The increase in T/sub c/ in the range 0.05