THEORETICAL ELECTRONIC-STRUCTURE OF OXIDE BABIO3

In this paper, rye present a model simulation to understand the electr onic structure of BaBiO3. By treating two types of Bi sites with diffe rent valence configurations (6s(2) 6p(3) 6d(0) and 7s(0) 6p(3) 6d(0)), the valence instability in BaBiO3 is simulated. We show that an LMTO- ASA calculation can then give a semiconducting feature for this materi al 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+ sit es reduces greatly the overlapping integrals between Bi-6s-O-2p states and reduces correspondingly their band widths. The band gap appears b ecause the antibonding bands of Bi-6s-O-2p now Separate from the rest bands of Bi-O-2p.