The electronic bandstructures of hexagonal Ti3Se4 isotypic with Nb3S4 and of TiSe with the NiAs structure

A selfconsistent scalar-relativistic calculation of the energy-band structures of hexagonal Ti3Se4 isotypic with Nb3S4 and of hexagonal TiSe with the NiAs type structure has been performed by using the LMTO-ASA method. The results for Ti3Se4 are compared with the electronic band structures of the isotypic compounds V3S4 and V3S4. The differences between these band structures as well as with the band structure of TiSe are discussed. The calculated density of states at the Fermi level is found significantly lower than in the isotypic compounds V3S4 and Nb3S4. As is evidenced by the energy band calculations the one-dimensional character of Ti3Se4 is less pronounced than in the isotypic compounds M3S4 (M=V,Nb). Despite the shorter Ti-Ti separation within the linear metal atom chains in TiSe the energy bands are significantly less dispersive than in Ti3Se4.