Bond order in TiS2and FeTiS2

The nature of bonding in TiS 2 and its intercalation compounds FeTiS 2 is elucidated by calculating the bond orders defined by Godby and co-workers (1985) in the framework of an augmented plane-wave method. It is confirmed that in TiS 2 the Ti d gamma and S p states certainly make bonding and anti-bonding bands as suggested by Inglesfield (1980) on the basis of a tight-binding analysis. On intercalation the Fe d gamma states also make covalent-like bonds with S p states while the nature of bonding between the Ti d gamma and S p states is almost unchanged. It is also clarified that the Ti d in and Fe d in states form covalent-like bonds.