15min:

TINA ERICA ODAKA, TSUNEO HIRANO, Department of Chemistry, Faculty of Science, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan; PER JENSEN, Institute for Astrophysics and Planetary Sciences, Ibaraki University, 2-1-1 Bunkyo, Mito 310-8512, Japan.

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We have used the RENNER program system to make a detailed calculation of the rovibronic energies in the first excited electronic state, ² , of the MgNC radical. This calculation was based on recent ab initio surfaces (MR-SDCI(+Q)/[TZ3P+f(Mg), aug-cc-pVQZ(N and C)]) for the Renner-degenerate electronic states. Previous calculations of vibronic energies^c employing the same ab initio data in conjunction with perturbation expressions suggested that an observed band belonging to the ^{2 2 +} electronic transition \footnoteR.~R.~Wright and T.~A.~Miller, J.~Mol.~Spectrosc. 194, 219 (1999) should be reassigned. The present work confirms this conclusion which is further substantiated by the rotational structures calculated in the vibronic states, and by Franck-Condon theory predicting relative intensities. ² MgNC affords an example of the ``classic'' Renner effect involving component electronic states with linear equilibrium geometries. We present detailed analyses of rovibronic wavefunctions aimed at providing further insight into the nature of the Renner interaction.