6533b831fe1ef96bd12980c8

RESEARCH PRODUCT

Applications of Quantum Chemistry in Spectroscopy: Molecules, Complexes of Van der Waals, trapped Molecules

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I described in this memory my activities as a researcher at Tomsk well before 2003, in succession to the State University of Tomsk in the Faculty of Physics, Institute of Physics of Siberia, and the Institute of 'Atmospheric Optics, in France since then, mostly at the University of Bourgogne (ICB), but also at the University of Lille I (PhLAM) and the University of Marne-la-Vallée (LCT). Part of my work has been dedicated to the evaluation by calculating ab initio of rovibrational constants for quasi-spherical molecules. The centrifugal distortion constants and the dipole moment of the molecule SO2F2 were calculated to validate the tensor theory and interpreter the spectrum. I twas shown that ab initio calculations can provide rovibrational constants with satisfactory accuracy for the needs of high-resolution spectroscopy. The ab initio calculations are a priori an interesting source of additional data. I also presented the results of ab initio calculations for the anharmonic force field and equilibrium structure of the molecule C2H3Br. The structure calculated by least squares of the of the semi-experimental inertia moments with the vibration-rotation interaction constants deduced from ab initio calculations combined with experimental rotational constants shows a very good accuracy. This strategy in which the force field provided by the ab initio calculation is used to evaluate the rotational constants obtained from experimental data so far as asserting an attractive method for calibrating the physical constants. Much of my work was to seek and exploit new opportunities for the detection of molecules and complexes in the gas phase. In this context, the various electronic and vibrational states of molecules and complexes have been studied by ab initio methods. We have attempted to better understand the photophysics induced by radiation and the applicability of the method of photofragmentation. The wavelengths for some of photofragmentation processes have been proposed. The results are important for the detection of minor components in the atmosphere and may contribute to the modeling of the thermal balance of the atmosphere. The section on complex CH4 - N2 has been to obtain the surface potential of the complex for different configurations by ab initio calculations and to study properties such as dipole moment, polarizability and hyperpolarisabilité complex. The potential surface is obtained based on ab initio calculation at "Coupled Cluster CCSD (T)" and on a type aug-cc-pV(X)Z. The analytical form of the corresponding potential has been proposed. The analysis of the potential surface determines the family of the most stable configurations corresponding to the rotation of the N2 molecule around the x axis. The harmonic and anharmonic frequencies are calculated for the most stable configuration. The asymmetry parameter K = (2B - A - C) / (A - C) = -0.99 is very close to -1, which corresponds to a quasi-symmetric prolated top. This work can contribute to studies on the enlargement of rovibrational bands and presents a contribution to the fundamental understanding of the interaction of spherical molecules like methane with a molecules forming planetary atmospheres. The part concerning the adsorption on the zeolite contains my results on the modeling of the silicalite-1 and the adsorption of ethylene. These results show the importance to choose both the zeolite model and the level of theory to get the right answer spectroscopy. It was shown that adsorption of the molecule non-polar ethylene corresponds to a physisorption process and in the case of adsorption on silicalite-1, there is no privileged sites. Therefore, the calculations should be performed on different orientations of the molecules. Changes in spectra of adsorbate / adsorbent and interpretations were presented. The displacement caused by the interaction of the molecule with the silicalite tend to most modes of vibration to lower frequencies. The silicalite-1 can adsorb up to 11 molecules per cell. Therefore, under high loadining, the interactions between molecules play an important role. This means that we must also simulate the adsorption of two or more molecules of ethylene.