Journal of Chemical Physics, Vol.109, No.3, 919-927, 1998
The effect of spin-orbit coupling the magnetic properties of H2Ti(mu-H)(2)TiH2
Excited states of singlet and triplet H2Ti(mu-H)(2)TiH2 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 state singlet-first excited triplet energy gap is predicted. Orbital interactions responsible for spin-orbit coupling effects are identified;