| Autor: |
Ben Krid A; Université Gustave Eiffel, COSYS/LISIS, 5 Bd Descartes, 77454 Champs sur Marne, France., Ajili Y; Laboratoire de Spectroscopie Atomique, Moléculaire et Applications LSAMA, Université de Tunis Al Manar, Tunis, Tunisia., Ben Abdallah D; Université de Tunis, Ecole Nationale Supérieure d'Ingénieurs de Tunis, Laboratoire de Spectroscopie et Dynamique Moléculaire (LSDM), 5 Av. Taha Hussein, 1008 Tunis, Tunisia., Dhib M; Université de Tunis, Ecole Nationale Supérieure d'Ingénieurs de Tunis, Laboratoire de Spectroscopie et Dynamique Moléculaire (LSDM), 5 Av. Taha Hussein, 1008 Tunis, Tunisia., Aroui H; Université de Tunis, Ecole Nationale Supérieure d'Ingénieurs de Tunis, Laboratoire de Spectroscopie et Dynamique Moléculaire (LSDM), 5 Av. Taha Hussein, 1008 Tunis, Tunisia., Hochlaf M; Université Gustave Eiffel, COSYS/LISIS, 5 Bd Descartes, 77454 Champs sur Marne, France. |
| Abstrakt: |
A new 3D-potential energy surface (3D-PES) for the weakly bound CH 3 Cl-He complex is mapped in Jacobi coordinates. Electronic structure calculations are performed using the explicitly correlated coupled clusters with single, double, and perturbative triple excitations approach in conjunction with the aug-cc-pVTZ basis set. Then, an analytical expansion of this 3D-PES is derived. This PES shows three minimal structures for collinear C-Cl-He arrangements and for He located in between two H atoms, in the plane parallel to the three H atoms, which is near the center of mass of CH 3 Cl. The latter form corresponds to the global minimum. Two maxima are also found, which connect the minimal structures. We then evaluated the pressure broadening coefficients of the spectral lines of CH 3 Cl in a helium bath based on our ab initio potential. Satisfactory agreement with experiments was observed, confirming the good accuracy of our 3D-PES. We also derived the bound rovibronic levels for ortho- and para-CH 3 Cl-He dimers after quantum treatment of the nuclear motions. For both clusters, computations show that although the ground vibrational state is located well above the intramolecular isomerization barriers, the rovibronic levels may be associated with a specific minimal structure. This can be explained by vibrational localization and vibrational memory effects. |
