Ti(12)C(68): A stable T(h)-symmetry hollow cage

A stable T(h)-symmetry Ti(12)C(68) cage was systemically investigated using density functional theory. The structure of Ti(12)C(68) is a hollow cage with twelve TiC(13) subunit of three pentagons and one hexagon. The calculated frequencies are in the range 95.1 cm(−1)–1423.9 cm(−1). There are no imaginary frequencies, showing its kinetic stability. Ab initio molecular dynamics simulations demonstrate that the topological structure of cage-like Ti(12)C(68) cluster was well maintained when the effective temperature is up to 1139 K. The natural bond orbitals analysis shows that the d orbit of Ti atoms form four σ bonds with the neighboring four carbon atoms in each TiC(13) subunit playing an important role in the cluster stability. The molecular frontier orbitals analysis indicates that Ti(12)C(68) cage has a narrow HOMO-LUMO gap with metal-like property. It would be expected to enrich the species of hollow metal carbide clusters.