STRUCTURE AND STABILITY OF SMALL TITANIUM OXYGEN CLUSTERS STUDIED BY AB-INITIO QUANTUM-CHEMICAL CALCULATIONS

Ab Initio calculations have been performed on TinO2n-delta clusters, with n = 1-3 and delta = 0, 1, as well as some of their ionized species. The geometries of the different clusters were optimized, and vibrational analyses were performed at the ground-state equilibrium geometries. It was shown that the Ti-O bond lengths are essentially determined by the coordination numbers of the respective atoms, independent of n. The clusters are characterized by having very low pendant oxygen vibrational frequencies. The ionization energies for the (TiO2)n Clusters were significantly higher than those of oxygen-deficient, TinO2n-1, clusters. Some anomalous features of the n = 1 cluster, TiO2, as compared to clusters with n > 1, are discussed. Recent experimental mass spectrometric observations on titanium oxide clusters are discussed in the light of the present findings.