THEORETICAL APPROACH OF THE ROTATIONAL ENERGY LEVELS OF $SiC_{2}$
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Date
1993
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Publisher
Ohio State University
Abstract
In the T-shaped $SiC_{2}$ molecule, it is conjectured that the $C_{2}$ fragment is bound to the silicium atom by an ionic essentially non directional bound, and thus could rotate within the $molecule.^{1}$ The $\nu_{3}$ mode, corresponding to this internal rotation, might, therefore, be a large amplitude motion and this could explain the difficulties encountered in fitting the microwave spectrum of this molecule in the ground vibrational $state^{2}$ as well as in the $v_{3}-1$ vibrational $state.^{1}$ In an attempt to calculate the rovibrational energy levels of the $SiC_{2}$ molecule, a formalism will be derived in which the $\nu_{3}$ mode is treated as a large amplitude motion. This requires accounting for the two main features of the $SiC_{2}$ dynamics: the strong dependence of the inverse moment of inertia tensor on the angle of internal rotation and the Coriolis coupling between the large amplitude $\nu_{3}$ mode and the overall rotation of the molecule. The results obtained when using this formalism to fit the microwave $data^{1,2}$ will be discussed. The value obtained for the height of the potential barrier hindering the internal rotation will be reported and compared to the value given by ab initio $calculations.^{3}$
Description
$^{1}$ M. Bogey, C. Demuynck, J.-L. Destombes and A. D. Walters, Astron. Astrophys. 247, L13-L16 (1991). $^{2}$ C. A. Gottlieb, J. M. Vrtilek and P. Thaddeus, Astrophysical Journal 343, L29-L32 (1989). $^{3}$ A. J. Sadlej, G. H. F. Diercksen, J. Oddershede, and J. R. Sabin, Chem. Phys. 122, 297-304 (1988).
Author Institution: Laboratoire de Physique Mol\'{e}culaire et Applications, Universit\'{e} Pierre et Marie Curie et CNRS
Author Institution: Laboratoire de Physique Mol\'{e}culaire et Applications, Universit\'{e} Pierre et Marie Curie et CNRS