Ab initio potential energy surface, infrared spectra, and dynamics of the ion-molecule complexes between Br - and H 2, D 2, and HD

T. A. Grinev, A. A. Buchachenko, J. Kłos, E. J. Bieske

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Abstract

A three-dimensional potential energy surface (PES) for the Br --H 2 complex is computed using the ab initio CCSD(T) method and an extended basis set. The PES has two equivalent minima at the linear geometries (equilibrium interfragment distance R e=3.34 Å and interaction energy D e=610 cm -1) separated by the barrier at the T-shaped configuration (interfragment distance R e=4.03 A and barrier height of 610 cm -1). Ab initio points are fitted to a flexible analytical form and used in the variational rovibrational energy level calculations. Simulated infrared spectra of the Br --H 2 and Br --D 2 complexes in the monomer stretching excitation region are in good agreement with the measured ones. Nonstatistical intensity ratios of the complexes of para- and ortho-monomers are qualitatively explained by monomer ligand exchange reactions. Predissociation of the complexes containing vibrationally excited monomers is analyzed and shown to proceed through the near-resonant vibration-to-rotation energy transfer. For complexes involving Br - and the HD monomer, two energetically low-lying states are predicted, corresponding predominately to the Br --DH and Br --HD isomeric forms. The results demonstrate the close similarity of the bromide containing complexes to their analogs containing the chloride anion.

Original languageEnglish
Article number114313
JournalJournal of Chemical Physics
Volume125
Issue number11
DOIs
Publication statusPublished - 2006
Externally publishedYes

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