Interpretation of ESCA spectra for non-stoichiometric titanium carbides on the basis of MO—LCAO calculations

The results of electron structure calculations for the single clusters TiC₆^20?, TiC₅□^16?, TiC₄□₂^12?, TiC3□3^8?, TiC₅□^16.64?, TiC₄□₂^13.32?; and double clusters Ti₂C₁₀^32?, Ti₂C₈□₂^24?, Ti₂C₁₀□^32.72? and Ti₂C₈□₂^24.80? by the semi-empirical Mulliken—Wolfsberg—Helmholtz method with self-consistency of charges and configurations are given. The data obtained are compared with measurements of the Ti 2p-level binding energies and X-ray photoelectron valence band spectra for TiC_x(x = 0.86–0.97). The variation of the metal atom charge in the limits of the homogeneity region for TiC and the appearance of this effect as a chemical shift of the Ti 2p-level are discussed. A special set of cluster calculations was performed to check the possibility of Ti valency variation in the homogeneity region of TiC_x.