Calculations of the electronic structure and superconducting properties of BaPb sub 1 minus x Sb sub x O sub 3

We have performed a band-structure calculation of the cubic perovskite compound BaSbO{sub 3} by the augmented-plane-wave method. Using these results we have constructed an accurate tight-binding Hamiltonian which we used to calculate the density of states of the alloy BaPb{sub 0.75}Sb{sub 0.25}O{sub 3} by the coherent-potential approximation. We have also calculated the electron-phonon coupling and found that such coupling can explain the low transition temperature {ital T}{sub {ital c}} of this alloy system and the higher {ital T}{sub {ital c}} for the Bi-doped alloy. A prediction is made for a much higher transition temperature for Sb- or Bi-rich alloys.