A theoretical study for H2 + CN ↔ HCN + H reaction and its kinetic isotope effects with variational transition state theory

Li Ping Ju, Ke Li Han, John Z.H. Zhang

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We present variational transition state theory (VTST) calculations for the H2 + CN → HCN + H (R1) and H2 + CN → DCN + D (R2) reactions and their reverses based on a global many-body expansion potential energy surface (PES) for ground-state H2CN (ter Horst MA, Schatz GC, Harding LB, J Chem Phys 105:658, 1996). It is found that the tunneling effects are negligible over the 200-2000 K temperature range and non-negligible over 100-200 K for R1 and R2 reactions. The C-N bond acts almost as a spectator for both reactions. The present VTST rate constants are in good agreement with the available experimental results and the previous theoretical predictions for R1 and R2 reactions except for the overestimation of rate constants by VTST at lower temperatures that may be caused by recrossing effect. Additionally, the kinetic isotope effects are important for the forward R1 and R2 reactions, but not for the reverses of R1 and R2.

Original languageEnglish (US)
Pages (from-to)769-777
Number of pages9
JournalJournal of Theoretical and Computational Chemistry
Issue number4
StatePublished - Dec 2006


  • Kinetic isotope effects
  • Rate constants
  • VTST

ASJC Scopus subject areas

  • Computer Science Applications
  • Physical and Theoretical Chemistry
  • Computational Theory and Mathematics


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