MOLECULAR-STRUCTURES OF 10-VALENCE ELECTRON SPECIES .4. POTENTIAL-ENERGY SURFACES AND PROPERTIES OF HSIX(+)(X=O, S, SE)

Potential energy surface (PES) searches of HSiX (X = O, S, Se) ions we re performed using HF and MP2 computational methods. Split-valence tri ple-zeta isotropic basis sets augmented by sets of p and d polarizatio n functions on hydrogen atoms and sets of d and f polarization functio ns on heavy atoms (TZP(2d,2p) and TZP(2df,2pd)) were used. Unlike thos e of the linear form of HOSi+, the strongly bent HSSi+ and HSeSi+ glob al minimum-energy structures are predicted at both HF and correlated l evels of theory, in contradiction to Mulliken-Walsh's rules. Isomeric HSiS+ and HSiSe+ forms are higher-energy local minima on the studied P ESs.