THE ELECTRONIC CHEMICAL-POTENTIAL AS A BASIS FOR A CLUSTER MODEL APPROXIMATION FOR INTERCALATION OF LI IN 1T-TIS2

The representation of the electronic structure of intercalated 1T - Ti S2 with lithium by a cluster approximation is discussed. The electroni c chemical potential, defined in the context of density functional the ory, is used as a criterion to determine the minimal units that retain the major electronic properties of the actual solid. The results indi cate that a structure containing 3-4 hexagonal unit cells of TiS2, wit h an octahedral coordination around the transition metal, is good enou gh to reproduce the major features of the electronic structure of the infinite layered solid. Analysis of the valence and conducting bands s hows good qualitative agreement with band theory calculations. A parti al electron transfer from Li to the lattice is predicted, in good agre ement with experimental NMR data for this system.