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 C_2v 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.