Electronic properties and X-ray absorption spectra of Ba1-xKxBiO3

The band structure, the density of states, and X-ray absorption spectra of the oxygen K-edge for perovskite high-temperature superconductors based on BaBiO3 are calculated by the density functional theory method for different levels of potassium doping in the ground and optically excited states. It is shown that changes in the properties of the electronic subsystem near the Fermi level can be correctly described by taking into account local structural inhomogeneities caused by doping and exposure to optical radiation. The appearance with doping of hole carriers on the hybridized Bi6s - O2pσ* orbital is demonstrated, which agrees with the model of the electronic structure of bismuthate high-temperature superconductors based on a spatially separated Fermi-Bose mixture.