SCF ab initio quantum mechanical calculation of equilibrium geometry, vibrational frequencies and infrared intensities for the thiophosphate ions PS 3− and PS 43−

Abstract

Several SCF basis sets up to a McLean-Chandler “triple split” basis set with diffuse orbitals and polarization functions were employed to calculate energy, geometry and vibrational frequencies for PS 3 − and PS 4 3−. The best calculated frequencies were within 10% of the experimental values, and a reassignment of the observed frequencies for PS 3 − was performed on the basis of these calculations. Polarization functions are imperative to give an acceptable geometry, but minimal basis sets (STO-5G) yield surprisingly good predictions of vibrational frequencies. STO-5G * generally gives ca. 0.05 Å shorter bond lengths than the split valence basis sets and gives too high stretching, but acceptable bending frequencies. There are almost no differences in the geometry and moderate differences in the vibrational frequencies obtained by the different split valence basis sets.