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# Ab initio study of a quasi van der Waals molecule: $N_{2}O_{4}$

Please use this identifier to cite or link to this item: http://hdl.handle.net/1811/13755

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 Title: Ab initio study of a quasi van der Waals molecule: $N_{2}O_{4}$ Creators: Elyoussoufi, Y.; Lievin, J.; Herman, M. Issue Date: 1996 Abstract: A critical review of the ab initio literature on the ground electronic state of $N_{2}O_{4}$ is presented. It is completed by new calculations including higher order electron correlation effects using the MP4 and internally-contracted MRCI methods and some open questions are revisited. They concern the harmonic and anharmonic force fields, the torsional energy barrier, the dissociation path into two $NO_{2}$ radicals and the assignment of the IR spectrum. Most properties affected by the quasi van der Waals nature of the NN bond are shown to require a high level of theory (MRCI/cc-pVTZ). Reliable harmonic vibrational frequencies (within 3%) are however obtained from the MP4/6-31$G^{*}$ method. This level has been adopted to calculate the IR spectrum from anharmonic variational calculations within a 4 dimensional effective model. An unambiguous assignment of the experimental $spectrum^{a}$ below $600 cm^{-1}$ is proposed. URI: http://hdl.handle.net/1811/13755 Other Identifiers: 1996-WG-15