AN AB INITIO STUDY OF THE $\tilde{A} ^{2}\Pi$ STATE AND THE $\tilde{A} ^{2}\Pi\leftarrow\tilde{X} ^{2}\Sigma^{+}$ ELECTRONIC TRANSITION OF MgNC
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Date
2001
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Publisher
Ohio State University
Abstract
We have used the RENNER program $system^{b}$ to make a detailed calculation of the rovibronic energies in the first excited electronic state, $\tilde{A} ^{2}\Pi$, of the MgNC radical. This calculation was based on recent ab initio surfaces $(MRSDCI(+Q)/[TZ3P+f(Mg)$, aug-cc-$pVQZ(N and C)])^{c}$ for the Renner-degenerate electronic states. Previous calculations of vibronic $energies^{c}$ employing the same ab initio data in conjunction with perturbation $expressions^{d}$ suggested that an observed band belonging to the $\tilde{A} ^{2}\Pi\leftarrow\tilde{X} ^{2}\Sigma^{+}$ electronic $transition^{e}$ 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. $\tilde{A} ^{2}\Pi$ MgNC affords an example of the ``classic'' Renner $effect^{f}$ 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.
Description
$^{a}$Special Visiting Professor of the Japanese Ministry of Education, Science and Culture, October-December 2000. Permanent address: FB 9 - Theoretische Chemie, Bergische Universit\""at - Gesamthochschule Wuppertal, D-42097 Wuppertal, Germany. $^{b}$See, for example, P. Jensen, G. Osmann, and P. R. Bunker, in: ``Computational Molecular Spectroscopy'' (P. Jensen and P. R. Bunker, eds.), Wiley, Chichester, 2000, and references therein. $^{c}$T. E. Odaka, T. Taketsugu, T. Hirano, and U. Nagashima, J. Chem. Phys., submitted for publication. $^{d}$J. T. Hougen and J. P. Jesson, J. Chem. Phys. 38, 1524 (1963) $^{e}$R. R. Wright and T. A. Miller, J. Mol. Spectrosc. 194, 219 (1999) $^{f}$R. Renner, Z. Physik 92, 172 (1934)
Author Institution: Institute for Astrophysics and Planetary Sciences, Faculty of Science, Ochanomizu University; Department of Chemistry, Faculty of Science, Ochanomizu University; Department of Chemistry, Ibaraki University
Author Institution: Institute for Astrophysics and Planetary Sciences, Faculty of Science, Ochanomizu University; Department of Chemistry, Faculty of Science, Ochanomizu University; Department of Chemistry, Ibaraki University