The Geometry and Force Field of Thioformaldehyde

✍ Scribed by Stuart Carter; Nicholas C. Handy

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 132 KB
• Volume: 192
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1998.7692

✦ Synopsis

A six-dimensional variational code, recently presented for the determination of the rovibrational energy levels of formaldehyde, has been used to refine a quartic potential surface of thioformaldehyde and simultaneously to optimize its geometry. The parameters have been adjusted to obtain as good agreement as possible with the known J ϭ 0 vibrational energy levels and the corresponding observed J ϭ 1 rotational lines of both H 2 CS and D 2 CS, where known. This is a highly nonlinear problem, and it is not possible to refine separately the geometry and force field. We have simultaneously optimized the HCS bond angle, the quadratic force field, and a partial cubic and quartic force field. Fermi and Coriolis resonances have been reproduced. The predicted geometry is CH ϭ 1.0856 Å, CS ϭ 1.6110 Å, HCS ϭ 121.88°. Predictions are made for overtones and combination bands of H 2 CS and D 2 CS. Furthermore, a prediction is made for the unobserved fundamental 5 of D 2 CS, which lies very close to 3 6 .