An a b i n i t i o study of the harmonic force field and vibrational frequencies of thionylimide: Basis set and electron correlation effects

Abstract

Basis set and electron correlation effects on the geometry and harmonic force field of thionylimide (HNSO) are investigated in detail. d functions on S are essential in describing the bonding in this compound. The calculated Hartree–Fock vibrational frequencies are about 15% too high. Inclusion of electron correlation at the second and third order Moller–Plesset perturbation levels (MP2 and MP3) gives vibrational frequencies within 5% of experiment. A careful analysis of the force constants reveals that the experimentally derived force fields need some revision.