Definitive thermochemistry and kinetics of the interconversions among conformers of n-butane and n-pentane

Roland Tóbiás, A. Császár, László Gyevi-Nagy, G. Tasi

Research output: Contribution to journalArticle

Abstract

The focal-point analysis (FPA) technique is used for the definitive characterization of conformational interconversion parameters, including activation energy barriers, activation free energies, and kinetic rate coefficients at 298 K, of two n-alkanes, n-butane, and n-pentane, yielding the first complete analysis of their interconversion kinetics. The FPA implementation developed in this study is based on geometry optimizations and harmonic frequency computations carried out with density functional theory methods and single-point energy computations up to the CCSD(T) level of electronic structure theory using atom-centered Gaussian basis sets as large as cc-pV5Z. The anharmonic vibrational computations are carried out, at the MP2/6-31G* level of theory. Reflecting the convergence behavior of the Gibbs free-energy terms and the interconversion parameters, well-defined uncertainties, mostly neglected in previous theoretical studies, are provided. Finally, the effect of these uncertainties on the concentrations of the conformers of n-butane and n-pentane is examined via a global Monte–Carlo uncertainty analysis.

Original languageEnglish
Pages (from-to)424-437
Number of pages14
JournalJournal of Computational Chemistry
Volume39
Issue number8
DOIs
Publication statusPublished - Mar 30 2018

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Keywords

  • focal-point analysis
  • interconversion rate coefficients
  • n-alkanes
  • thermochemistry
  • uncertainty analysis

ASJC Scopus subject areas

  • Chemistry(all)
  • Computational Mathematics

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