Vacant outer orbitals in oxy anions of silicon,phosphorus, sulfur,and chlorine

The ions MO₄ ^n–, where M = Si, P, S, and Cl, have been calculated by a nonempirical Hartree-Fock method with the inclusion of the vacant 3d and 4s AO's of the central atom in the basis set. The calculations have shown that an increase in the role of the vacant outer molecules in M-O chemical bonding occurs.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 26, No. 2, pp. 233–236, March–April, 1990.