Structure of small TiC n clusters: A theoretical study

A theoretical study of the TiC _n ( n = 1-8) clusters has been carried out at the B3LYP/6-311+G(d) level. Molecular properties for three different isomers, namely linear, cyclic, and fan species, have been determined. The fan isomers, where the titanium atom is essentially side-bonded to the entire C _n unit, are predicted to be more stable than both linear and cyclic isomers. Only for the largest studied species, TiC ₈, the cyclic isomer is located lower in energy. An even-odd parity effect in the incremental binding energies is observed for the three isomers, n-even species being in general more stable for linear and fan isomers, whereas for the cyclic species n-odd clusters are favoured. A topological analysis of the electronic charge density shows that all cyclic isomers correspond to true monocyclic rings, whereas for the fan species a variety of different connectivities has been observed.