MOLECULAR AND ELECTRONIC-STRUCTURE OF SOME BINARY POLYHEDRAL CLUSTERS

The molecular and electronic structures of some polyhedral alternate m olecules X(n)Y(n), where n = 12, 16; x = B, Al, Si; Y = N, P, C, and o f homoatomic clusters C-24, Si-24, C-32, and Si-32 are calculated in a valence approximation by the MNDO method II is suggested that the sig ma-frameworks of these molecules are formed of four- and six-membered rings, with each X atom having only Y atoms as neighbors. The singlet states of all these systems have local minima on the corresponding pot ential energy surfaces with T-h symmetry for n = 12 and T-d symmetry f or n = 16. The main structural parameters, heats of formation, ionizat ion potentials, and effective charge distributions are given. It is co ncluded that the X(n)Y(n) heteroatomic clusters can exist when X and Y are atoms of Group III and V elements, respectively, or both are atom s of Group IV elements.