Potential energy surface and rovibrational calculations for the Mg +- H2 and Mg+- D2 complexes

V. Dryza, E. J. Bieske, A. A. Buchachenko, J. Kos

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A three-dimensional potential energy surface is developed to describe the structure and dynamical behavior of the Mg +-H2 and Mg +-D 2 complexes. Ab initio points calculated using the RCCSD(T) method and aug-cc-pVQZ basis set (augmented by bond functions) are fitted using a reproducing kernel Hilbert space method [Ho and Rabitz, J. Chem. Phys. 104, 2584 (1996)] to generate an analytical representation of the potential energy surface. The calculations confirm that Mg +-H2 and Mg +-D2 essentially consist of a Mg + atomic cation attached, respectively, to a moderately perturbed H2 or D2 molecule in a T-shaped configuration with an intermolecular separation of 2.62 and a well depth of De = 842 cm -1. The barrier for internal rotation through the linear configuration is 689 cm -1. Interaction with the Mg + ion is predicted to increase the H2 molecules bond-length by 0.008 . Variational rovibrational energy level calculations using the new potential energy surface predict a dissociation energy of 614 cm -1 for Mg +-H2 and 716 cm -1 for Mg +-D2. The H-H and D-D stretch band centers are predicted to occur at 4059.4 and 2929.2 cm -1, respectively, overestimating measured values by 3.9 and 2.6 cm -1. For Mg +-H2 and Mg +-D2, the experimental B and C rotational constants exceed the calculated values by ∼1.3, suggesting that the calculated potential energy surface slightly overestimates the intermolecular separation. An ab initio dipole moment function is used to simulate the infrared spectra of both complexes.

Original languageEnglish
Article number044310
JournalJournal of Chemical Physics
Issue number4
Publication statusPublished - 28 Jan 2011
Externally publishedYes


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