Effective Valence Shell Hamiltonian Calculations on Spin-Orbit Coupling of SiH, SiH+, and SiH2+

Abstract

Recently the ab initio effective valence shell Hamiltonian method H v has been extended to treat spin-orbit coupling in atoms or molecules. The quasidegenerate many-body perturbation theory based H v method has an advantage of determining the spin-orbit coupling energies of all valence states for both the neutral species and its ions with a similar accuracy from a single computation of the effective spin-orbit coupling operator. The new spin-orbit H v method is applied to calculating the fine structure splittings of the valence states of SiH, SiH + , and SiH 2 + not only to assess the accuracy of the method but also to investigate the spin-orbit interaction of highly excited states of SiH species. The computed spin-orbit splittings for ground states are in good agreement with experiment and the few available ab initio computations. The ordering of fine structure levels of the bound and quasi-bound spin-orbit coupled valence states of SiH and its ions, for which neither experiment nor theory is available, is predicted.