Theoretical electronic structure of oxide BaBiO3

In this paper, we present a model simulation to understand the electronic structure of BaBiO3. By treating two types of Bi sites with different valence configurations (6s2 6p3 6d0 and 7s0 6p3 6d0), the valence instability in BaBiO3 is simulated. We show that an LMTO-ASA calculation can then give a semiconducting feature for this material and a good estimation of the gap, which is 1.6 eV from the present model compared with 2.0 eV from experiments. The existence of Bi3+ sites reduces greatly the overlapping integrals between Bi6s-02p states and reduces correspondingly their band widths. The band gap appears because the antibonding bands of Bi6s-02p now separate from the rest bands of Bi-02p.