AN AB INITIO PREDICTION OF SPECTROSCOPIC CONSTANTS OF MgNC: THE FIRST Mg-BEARING MOLECULE IN SPACE
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Date
1993
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Publisher
Ohio State University
Abstract
In collaboration with Kawaguchi et al.'s microwave identification of MgNC as the first Mg-bearing molecule in space (1993), we carried out ab initio molecular orbital calculations of spectroscopic constants at the correlated level for the tri-atomic molecules of Mg, C and N. Three stationary points have been located by ROHF/TZ2P calculations, i.e., a linear MgNC $(^{2}\Sigma^{+})$, a linear MgCN $(^{2}\Sigma^{+})$ and the transition state between them. Relative energies calculated at the SDCl+Q/TZ2P level are 0 (MgNC), 510 (MgCN), and $2171 cm^{-1}$ (the transition state), respectively. The predicted SDCl/TZ2P values for the $X{^{2}}\Sigma^{+}$ MgNC are as follows: rotational constant $B_{0} = 5939.7$ MHz, centrifugal distortion constant $D_{0} = 0.0029$ MHz, Coriolis coupling constants $\zeta_{21} = -0.9588$ and $\zeta_{23} = 0.2842$ MHz, dipole moment $\mu_{c} = 5.22$ Debye, and harmonic frequencies $2189 (\omega_{1}), 83.3 (\omega_{2})$, and $539 cm^{-1} (\omega_{3})$. The predicted $B_{0}$ and $D_{0}$ values agree well with the experimental measurements. The very low $\omega_{2}$ value in the bending motion indicates that $X ^{2}\Sigma^{+}$ MgNC is a floppy molecule.
Description
Author Institution: Department of Industrial Chemistry, Faculty of Engineering, University of Tokyo; Department of Chemistry, Faculty of Science, Ochanomizu University; Department of Information Sciences, Faculty of Science, Ochanomizu University; Department of Information Sciences, Faculty of Science, Institute for Fundamental Chemistry