A theoretical study of BrCN+ in the (2)Pi electronic ground state: Large amplitude bending motion

作者：Hirano Tsuneo; Okuda Rei; Nagashima Umpei; Nakashima Yoshihiro; Tanaka Kelichi; Jensen Per^*

来源：Journal of Molecular Spectroscopy, 2007, 243(2): 202-218.

DOI：10.1016/j.jms.2007.02.006

• ab initio
• BrCN+
• electronic ground state
• rotation-vibration energies
• structure
• MORBID
• RENNER

We have calculated the three-dimensional potential energy surfaces for the 1 (2)A' and 1 (2)A" states of BrCN+ at the MR-SDC1_DK+Q/ [QZP-ANO-RCC (Br, C, N)] level of theory, where MR-SDCI_DK means 'multi-reference single and double excitation configuration interaction calculation with Douglas-Kroll Hamiltonian.' These ab initio potential energy surfaces have a common minimum (corresponding to the X-2 II state) at a linear equilibrium structure with r(e)(Br-C) = 1.735 angstrom and r(e)(C-N) = 1. 199 angstrom. Variational RENNER calculations yield a zero-point averaged structure (with the structural parameters calculated as expectation values over rovibrational wavefunctions) with < r(Br-Q)> o = 1.739 angstrom, r(C-N)> = 1.204 angstrom, and r(e)(<(Br-C-N)> o = 172(4)degrees. A severe Fermi resonance between 2v(2) and v(3) has been found theoretically for the 2 A" potential energy surface. Comparing the ab initio zero-point averaged structure with a recent, experimentally derived ro structure, it is concluded that the effects of large-amplitude bending motion should be taken into account explicitly in the process of deriving the ro structure from the experimental values of the rotational constants. The electronic structure of X-2 II BrCN+ has also been discussed.

• 出版日期2007-6