New potential energy surfaces for the ${\tilde X}$ and ${\tilde A}$ states of CH$_2^+$

Philip Bunker (1) , Wolfgang P. Kraemer (2) , Sergei N. Yurchenko (3) , Walter Thiel (4) , Christopher F. Neese (5) , Jennifer L. Gottfried (5) , Per Jensen (6)

1 The Steacie Institute for Molecular Sciences
2 Max Planck Institute for Astrophysics
3 TU Dresden - Technische Universität Dresden = Dresden University of Technology
4 Max-Planck-Institut für Kohlenforschung (Coal Research)
5 University of Chicago
6 FB C Theoretical Chemistry

We report new {\it ab initio} calculations of the three-dimensional potential energy surfaces for the Renner-effect coupled $\tilde{X}\,^{2}A_1$ ground electronic state and $\tilde{A}\,^{2}B_1$ first excited electronic state of the CH$_2^+$ molecule. We also make an {\it ab initio} calculation of the spin-orbit coupling surface $A_{\rm SO}(r_{12},r_{32},\rho)$ between these states. Using these {\it ab initio} surfaces in our computer program RENNER, we calculate term values and absorption line intensities, and compare with recently observed high resolution spectra. Adjusting two parameters in the potential surfaces we are able to achieve satisfactory agreement with the experimental results except for those that involve the ${\tilde A}$ state ($v_2^{\rm linear}$ = 8, $l$ = 1) vibronic level. The implication of this disagreement is discussed.

Mots clés: Physical Sciences

Philip Bunker, Wolfgang P. Kraemer, Sergei N. Yurchenko, Walter Thiel, Christopher F. Neese, et al.. New potential energy surfaces for the ${\tilde X}$ and ${\tilde A}$ states of CH$_2^+$. Molecular Physics, 2007, 105 (10), pp.1369-1376. ⟨10.1080/00268970701344534⟩. ⟨hal-00513093⟩