Accurate multireference calculations of the electronic structure of TiF2 and TiCl2

We report a systematic study of the electronic structure of two members of the transition metal dihalide family, TiF2 and TiCl2. Using the configuration interaction method in large basis sets we investigated the lowest 15 states of TiF2 and TiCl2. We report bond lengths, frequencies and dissociation energies of both molecules. For TiF2 we found a near degeneracy of the ground and the first excited state with a possible breakdown of the Born–Oppenheimer approximation.