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The Geometry and Force Field of Thioformaldehyde
1Department of Chemistry, University of Reading, Whiteknights, RG6 2AD, United Kingdom
Journal of Molecular Spectroscopy
|December 16, 1998
Summary
Researchers refined thioformaldehyde
Area of Science:
- Computational Chemistry
- Molecular Spectroscopy
Background:
- Accurate potential energy surfaces (PES) are crucial for understanding molecular behavior.
- Previous variational codes were developed for formaldehyde (H2CO).
Purpose of the Study:
- To refine the quartic potential surface of thioformaldehyde (H2CS).
- To simultaneously optimize the molecular geometry of thioformaldehyde.
- To accurately predict rovibrational energy levels and spectral lines.
Main Methods:
- A six-dimensional variational code was employed.
- Simultaneous optimization of geometry (HCS bond angle) and force field (quadratic, cubic, quartic).
- Fitting to experimental J=0 vibrational and J=1 rotational energy levels of H2CS and D2CS.
Main Results:
- A refined quartic potential surface for thioformaldehyde was obtained.
- The predicted geometry is CH = 1.0856 Å, CS = 1.6110 Å, HCS = 121.88 degrees.
- Fermi and Coriolis resonances were successfully reproduced, validating the model.
Conclusions:
- Simultaneous optimization of geometry and force field is necessary for thioformaldehyde.
- The refined potential surface enables accurate predictions of spectral properties.
- Predictions for overtones, combination bands, and the unobserved nu5 fundamental of D2CS are provided.