Molecular and electronic structure of TiH2

Abstract

Ab initio electronic structure calculations using correlated wave functions have been performed to investigate the structure and energetics of TiH2 in its low-lying electronic states. Several triplet states have been found to lie very close to each other in energy (within 5 kcal/mol) and nearly 1 eV below the lowest singlet state. The lowest quintet states appear to be considerably higher in energy. The ground state of TiH2 is found to be bent 3B1 in C2v symmetry, with the 3A1 state lying only 1 kcal/mol higher in energy. The lowest singlet state, 1A1, is found to be slightly bent, but with a very flat potential energy surface. The Ti–H bond in all TiH2 electronic states is predicted to be strongly polarized Ti+H−. The use of state-averaged multiconfigurational self-consistent field wave functions is essential to obtain a consistent picture of all electronic states of interest.