VALENCE ELECTRONIC STATES OF SIH-2-INITIO EFFECTIVE VALENCE SHELL HAMILTONIAN( BY AB)

The ab initio second order effective valence shell Hamiltonian which i s based on quasidegenerate many-body perturbation theory has been appl ied to the SiH2+, dication. From the characteristic properties of H(up silon), all the valence states are determined with a same accuracy. Th e four low lying quasibound states (X 2SIGMA+, A 2PI, a 4PI, C 2SIGMA) are found for the dication. It is verified that the existence of som e quasibound states is due to the interaction of an attractive state f rom ion-neutral pair asymptote with a same symmetry repulsive state fr om ion-ion pair asymptote. Since the experimental data are scarce, thi s work provides all theoretical spectroscopic properties of these quas ibound states. Also the repulsive valence states are examined.