This thesis aims at validating a theoretical protocol to develop global potential energy surfaces for use in the spectroscopy and dynamics of transition metal nitrosyl complexes. To get an insight into the homogeneous catalysis of NO with Cu and the chemical reaction dynamics, an accurate prediction of the nature of the interaction, as well as of the global potential energy surfaces (PES) is necessary in the gas phase. Experimental data are difficult to obtain, hence the importance of carrying out calculations of the lowest electronic states as accurate as possible to address the structure , spectroscopy and dynamics of this system. All ab initio calulations we report here were performed at the multi-reference configuration interaction (MRCI) and at the coupled cluster level of theory. We aslo investigate the importance of relativistic effects in the systems. For CuNO system, it is shown that a complete active space involving 18 valence electrons, 11 molecular orbitals and the prior determination of 12 roots in the MCSCF calculation is needed for overall qualitatively correct results from the MRCI calculations. The present calculations yield a bound singlet A' ground state for CuNO and comparared with previous results. We have obtained new, complete potential energy functions of the ground electronic states of CuO and CuN systems. Comparison of the term values for the lowest electronic states of CuO and CuN with those previously reported in the literature shows a quite good agreement. We derived a novel analytical representation of the adiabatic potential energy surface in the ground electronic state of the CuNO system as a sum of two-body and three-body terms. This compact and flexible representation enables us to make a physically correct interpolation of the ab initio data points at the MRCI level of theory. We use a modified Levenberg-Marquardt algorithm for fitting the potential, which has 19 adjustable parameters and which now enables us to do scattering dynamics of the CuNO system. We perform full dimensional quantum dynamical studies with this new potential. Convergence of the time dependent wavepacket calculation has been achieved. We find that the scattering in CuNO is highly inelastic. Intermediate, excited meta stable reaction products CuNO∗ live for about 0.5 to 1 ps and maybe more.
| Identifer | oai:union.ndltd.org:CCSD/oai:tel.archives-ouvertes.fr:tel-00954768 |
| Date | 20 December 2012 |
| Creators | Krishna, Balasubramoniam Murali |
| Publisher | Université de Strasbourg |
| Source Sets | CCSD theses-EN-ligne, France |
| Language | English |
| Detected Language | English |
| Type | PhD thesis |
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