The bending triad of the quasi-spherical top molecule SO2F2 in the 550 cm-1 region

International audienceThe analysis of the v(3)/v(7)/v(9) bending triad of SO2F2 has been recently performed with the Watson's Hamiltonian up to octic terms employing 79 rovibrational parameters but including only the first order Coriolis interaction terms, fixed to ab initio values [H. Burger, J. Demaison, F. Hegelund, L. Margules, I. Merke, J. Mol. Struct. 612 (2002) 133-141]. Since SO2F2 is a quasi-spherical top, it can also be considered as derived from the SO42- sulfate ion. We have thus developed a new tensorial formalism in the O(3) > Td > C2v group chain [M. Rotger, V. Boudon, M. Loete, J. Mol. Spectrosc. 216 (2002) 297-307]. This approach allows a systematic development of rovibrational interactions and makes global analyses easier to perform even for complex polyad systems. We present here an application of this model to the analysis of the bending triad, with the same set of microwave assignments and almost the same set of infrared assignments as in the previous study of Burger et al. It appears that we need to expand our Hamiltonian to a lower degree than the "classical" one (six instead of eight) when including also the second order Coriolis interactions. Our fit does not include more parameters. Furthermore, all of them are determined and the standard deviation of the rotational transitions is twice smaller. The analysis has been performed thanks to the C-2 upsilon TDS program suite, which is freely available at the URL: http://icb.u-bourgogne.fr/OMR/SMA/SHTDS/C2VTDS.html

Dipole Moment Surface of the van der Waals Complex CH4–N2

International audienc

Static polarizability surfaces of the van der Waals complex CH4–N2

International audienceThe static polarizability surfaces of the van der Waals complex CH4–N2 have been calculated for a broad range of intermolecular separations and configurations in the approximation of rigid interacting molecules. The calculations have been carried out at the CCSDT and MP2 levels of the theory using the aug-cc-pVTZ basis set with the BSSE correction and within the framework of the classical long-range multipolar induction and dispersion interactions. It was shown that the results of analytical polarizability calculations for the CH4–N2 complex are in a good agreement with the ab initio polarizabilities in the outer part of the van derWaals well on the complex potential surface. Ab initio calculations of the polarizability tensor invariants for the complex being in the most stable configurations were carried out. The change in the polarizability of CH4–N2 due to the deformation of the CH4 and N2 monomers at the formation of the complex was estimated. In the framework of the analytical approach the polarizability functions ¯ iiR of the free oriented interacting molecules CH4 and N2 were calculated

High-pressure synthesis of a polyethylene/zeolite nano-composite material

International audienc