AB-INITIO CALCULATION OF S-33 QUADRUPOLE COUPLING-CONSTANTS - REANALYSIS OF THE S-33 HYPERFINE-STRUCTURE IN THE ROTATIONAL SPECTRUM OF THIIRANE

We present quantum chemical calculations on the MP4(SDQ) level with ba sis sets of high local quality to determine the nuclear quadrupole cou pling tensor of S-33 series of molecules, which of were investigated u p to now by microwave spectroscopy. The analysis of the nuclear quadru pole coupling in the rotational spectra provided experimental informat ion on the tensors. As an example for such an analysis, improved value s for thiirane, (C2H4S)-S-33, are given: chi(aa)=-32.9425(78) MHz, chi (bb)=-16.402(14) MHz, chi(cc)=49.345(14) MHz.