THEORETICAL-STUDY OF THE EFFECTS OF LITHIUM INTERCALATION ON THE ELECTRONIC-STRUCTURE OF TIS2

The band structure of the intercalation complex of LiTiS2 has been computed using a semi-empirical tight-binding method and this is compared with the results of a revised TiS2 calculation. The results obtained confirm that changes in the basic electrical characteristics of TiS2, which occur when it is intercalated with lithium, can be attributed to a rigid-band filling of its lowest unoccupied electron states as has previously been proposed. However, they also suggest that intercalation can act to alter the nature and the dispersion of some of the energy bands in the unintercalated crystal. The bands which are most affected by the process are those which derive from orbitals which have the same symmetry as the lithium 2s orbital, namely, the titanium 4s conduction level and the tightly bound sulphur 3s levels.