The Effect of Spin-Orbit Coupling on the Magnetic Properties of H2Ti(μ–H)2TiH2

Excited states of singlet and triplet H2Ti(μ−H)2TiH2 have been calculated using multiconfigurational wave functions. The effects of orbital relaxation are determined by optimizing orbitals for all states separately and comparing to state-averaged calculations, and are found to be small. Dynamic electron correlation included through second-order perturbation theory is found to have a considerable effect on excited state relative energies, but not on the ordering of states. Spin-orbit coupling effects are introduced by a one-electron operator which uses an effective nuclear charge to replace two-electron effects. The resulting splittings of the lowest energy triplet state components are 0.027 and 0.199 cm−1, respectively. The former is due to the angular momentum operator which acts along the Ti–Ti axis; the latter is due almost entirely to the angular momentum operator which acts in the direction perpendicular to the plane of the Ti–H–Ti bridge. An overall ferromagnetic effect of 0.660 cm−1 on the ground statesinglet-first excited triplet energy gap is predicted. Orbital interactions responsible for spin-orbit coupling effects are identified.