A new potential energy surface for the CH3+H2↔CH4+H reaction: Calibration and calculations of rate constants and kinetic isotope effects by variational transition state theory and semiclassical tunneling calculations

1987 ◽  
Vol 87 (12) ◽  
pp. 7036-7049 ◽  
Author(s):  
Tomi Joseph ◽  
Rozeanne Steckler ◽  
Donald G. Truhlar
Keyword(s):  
Potential Energy ◽  
Rate Constants ◽  
Transition State Theory ◽  
Energy Surface ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
State Theory ◽  
Variational Transition State Theory ◽  
Kinetic Isotope ◽  
Semiclassical Tunneling

A THEORETICAL STUDY FOR H2 + CN ↔ HCN + H REACTION AND ITS KINETIC ISOTOPE EFFECTS WITH VARIATIONAL TRANSITION STATE THEORY

2006 ◽  
Vol 05 (04) ◽  
pp. 769-777 ◽  
Author(s):  
LI-PING JU ◽  
KE-LI HAN ◽  
JOHN Z. H. ZHANG
Keyword(s):  
Transition State ◽  
Rate Constants ◽  
Transition State Theory ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
State Theory ◽  
Variational Transition State Theory ◽  
Kinetic Isotope ◽  
Theoretical Predictions ◽  
Variational Transition State

We present variational transition state theory (VTST) calculations for the H 2 + CN → HCN + H (R1) and D 2 + CN → DCN + D (R2) reactions and their reverses based on a global many-body expansion potential energy surface (PES) for ground-state H 2 CN (ter Horst MA, Schatz GC, Harding LB, J Chem Phys105:558, 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.

Semiclassical and Quantum Mechanical Calculations of Isotopic Kinetic Branching Ratios for the Reactionof O(3P) with HD

1989 ◽  
Vol 44 (5) ◽  
pp. 427-434 ◽  
Author(s):  
Gillian C. Lynch ◽  
Philippe Halvick ◽  
Donald G. Truhlar ◽  
Bruce C. Garrett ◽  
David W. Schwenke ◽  
...  
Keyword(s):  
Transition State Theory ◽  
Energy Surface ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Branching Ratios ◽  
State Theory ◽  
Quantum Mechanical ◽  
Variational Transition State Theory ◽  
Least Action ◽  
Kinetic Isotope

Tunneling probabilities for the reactions O + HD → OH + D and O + DH → OD + H have been calculated by semiclassical dynamical methods and compared to accurate quantal calculations for the same potential energy surface. The results are used to test the reliability of variational transition state theory with the least-action semiclassical method for tunneling probabilities for the prediction of intramolecular kinetic isotope effects.

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