Stability, electronic structure, and vibrational modes of the Ti8C12 dimer -: art. no. 241404

We present our density-functional results of the geometry, electronic structure, and dissociation energy of Ti8C12 dimer. We show that as opposed to the currently held view that Ti8C12 are highly stable monodispersed clusters, the neutral Ti8C12 clusters form covalent bonds and form stable dimers. We determine that the Ti atoms bond weakly (0.9 eV/bond) to organic ligands such as ammonia. Alternatively the metallocarbohedrene (Met-Car) dimer has a cohesive energy of 4.84 eV or approximately 1.2 eV per bond. While Met-Car dimers are stable, formation of these dimers may be quenched in an environment that contains a significant population of organic ligands. The ionization and dissociation energies of the dimer are of the same order, which prevents the observation of the dimer in ion mass spectroscopy. The analysis of the vibrational frequencies show the lowest-energy structure to be dynamically stable. We also present infrared-absorption and Raman-scattering spectra of the Ti8C12 dimer.