Abstract
The electronic structure of BaTiS3 was investigated using a discrete-variational Xα (DV-X α) method on the model cluster. In the calculation of [Ba6Ti3S48]72- cluster, the band gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) was 0.98 eV, which was much smaller than that of ionic crystal, BaTiO3. In the valence band region, S 3p orbitals hybridized with Ti 3d orbitals, while not with atomic orbitals of Ba atom. Net charges calculated for the [Ba6Ti3S48]72- cluster were + 1.911 for Ba, + 0.750 for Ti and -0.682 for S, respectively. Furthermore, the bond overlap population of Ti-S bond was very large, compared with the Ti-Ti and Ba-S bonds. These results indicate that the covalent interaction between Ti and S atoms plays a dominant role on chemical bond of BaTiS3 crystal.
