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 Zhang

Research output: Contribution to journalArticle

Abstract

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
Volume5
Issue number4
DOIs
StatePublished - Dec 2006

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Isotopes
isotope effect
Rate constants
reaction kinetics
Potential energy surfaces
Kinetics
kinetics
Ground state
Temperature
potential energy
expansion
ground state
predictions
temperature

Keywords

  • Kinetic isotope effects
  • Rate constants
  • VTST

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

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title = "A theoretical study for H2 + CN ↔ HCN + H reaction and its kinetic isotope effects with variational transition state theory",
abstract = "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.",
keywords = "Kinetic isotope effects, Rate constants, VTST",
author = "Ju, {Li Ping} and Han, {Ke Li} and John Zhang",
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T1 - A theoretical study for H2 + CN ↔ HCN + H reaction and its kinetic isotope effects with variational transition state theory

AU - Ju, Li Ping

AU - Han, Ke Li

AU - Zhang, John

PY - 2006/12

Y1 - 2006/12

N2 - 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.

AB - 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.

KW - Kinetic isotope effects

KW - Rate constants

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