SCALED QUANTUM-MECHANICAL (SQM) CALCULATIONS AND VIBRATIONAL ANALYSESOF THE CAGE-LIKE MOLECULES P4S3, AS4SE3, P4SE3, AS4S3, AND PAS3S3

Geometry, vibrational frequencies, IR intensities and potential energy distribution are calculated for P4S3 at the SCF/6-31G level. With on e scaling factor all observed frequencies are modelled with an accurac y of +/- 1%, and a revised assignment is proposed. Transfer of the P4S 3 force field to P4Se3, As4Se3, As4S3, and PAs3S3 and rescaling yields a good fit for all these compounds. Where more than one scaling facto r is needed, the different scaling factors are explainable. Revised as signments and potential energy distribution data are given for all the se compounds. STO-3G calculations give a poorer fit for P4S3, but wi th separate scaling of stretching and bending force constants a good f it is obtained.