Stationary points for the OH- + CH3F → CH3OH + F- potential energy surface

Lipeng Sun, Kihyung Song, William L. Hase, Marcelo Sena, Jose M. Riveros

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21 Scopus citations

Abstract

Ab initio calculations at the HF, MP2, and CCSD(T) levels of theory, utilizing a range of basis sets including the large bases 6-311++G(2df,2pd) and aug-cc-pVTZ, are used to study the OH-+CH3F→CH3OH+F- potential energy surface (PES). Structures, vibrational frequencies, and energies are determined for the reactant and product asymptotic limits, the OH⋯CH3F ion-dipole potential minimum, the [OH⋯CH3⋯F]- central barrier, and the CH3OH⋯F- hydrogen-bonded minimum. This PES does not have a post-reaction F-⋯CH3OH minimum complementary to the pre-reaction OH-⋯CH3F minimum. Except for the CH3OH⋯F- minimum, the large basis sets and MP2 theory give a consistent set of structures and frequencies for the stationary points. Neither the structure nor the vibrational frequencies of the CH3OH⋯F- minimum are converged by the MP2 and large basis set calculations. RHF theory does not describe the energy of the [OH⋯CH3⋯F]- central barrier nor the reaction exothermicity, however, it does give OH-+CH3F→OH-⋯CH3F and F-+CH3OH→CH3OH⋯F- well depths in good agreement with the CCSD(T) values. Overall good agreement is found between the MP2/6-31+G* and much higher level CCSD(T) energies for the stationary points. The MP2 and CCSD(T) calculations give a reaction exothermicity and F-+CH3OH→CH3OH⋯F- well depth in good agreement with the experimental values.

Original languageEnglish
Pages (from-to)315-325
Number of pages11
JournalInternational Journal of Mass Spectrometry
Volume227
Issue number3
DOIs
StatePublished - Jul 1 2003

Keywords

  • Ion-dipole potential
  • Potential energy surface
  • S2 reactions

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