Density Functional Theory Study of Ti<sub>n</sub>O<sub>2n-m </sub>Clusters (n=1-4, m=0,1)

Abstract

Using density functional theory, the equilibrium geometries of TinO2n and TinO2n-1 clusters (n=1-4) have been obtained. It suggests that the structures of these two corresponding clusters are changed slightly, except for the number of terminal oxygen atoms. The electronic properties have also been investigated. The bond between Ti and terminal oxygen atom is found to be more covalent than other Ti-O bonds. It also indicates that by deleting one terminal oxygen atom, HOMO is mainly derived from titanium atoms with least coordination, but not from singly-coordination oxygen atoms as that in the stoichiometric clusters. Highest energy levels of least-coordination Ti atoms shift highly and they become more reactive. In addition, HOMO-LUMO energy gaps and binding energies were observed. The calculated results show that the energy gaps decrease quickly, except for Ti4O7 clusters and all the binding energies are relatively large.