Unimolecular Decomposition of Formaldehyde:  H2CO → H2+ CO. Part I:  Ab Initio Reaction Path and Variational Transition State Rate Constants

1998 ◽  
Vol 102 (52) ◽  
pp. 10805-10812 ◽  
Author(s):  
Leila M. M. de A. Martins ◽  
Graciela Arbilla ◽  
Edilson C. da Silva
Keyword(s):  
Transition State ◽  
Ab Initio ◽  
Rate Constants ◽  
Reaction Path ◽  
Unimolecular Decomposition ◽  
State Rate ◽  
Variational Transition State

scholarly journals Ab initio Variational Transition State Theory and Master Equation Study of the Reaction (OH)3SiOCH2 + CH3 ⇌ (OH)3SiOC2H5

2015 ◽  
Vol 229 (5) ◽  
Author(s):  
Daniel Nurkowski ◽  
Stephen J. Klippenstein ◽  
Yuri Georgievskii ◽  
Marco Verdicchio ◽  
Ahren W. Jasper ◽  
...  
Keyword(s):  
Transition State ◽  
Ab Initio ◽  
Master Equation ◽  
Rate Constants ◽  
Transition State Theory ◽  
Reaction Rate ◽  
State Theory ◽  
Variational Transition State Theory ◽  
Reaction Rate Constants ◽  
Variational Transition State

AbstractIn this paper we use variable reaction coordinate variational transition state theory (VRC-TST) to calculate the reaction rate constants for the two reactions, R1: (OH)

scholarly journals Association of Cl with C2H2by unified variable-reaction-coordinate and reaction-path variational transition-state theory

2020 ◽  
Vol 117 (11) ◽  
pp. 5610-5616
Author(s):  
Linyao Zhang ◽  
Donald G. Truhlar ◽  
Shaozeng Sun
Keyword(s):  
High Pressure ◽  
Transition State ◽  
Transition State Theory ◽  
Reaction Path ◽  
State Theory ◽  
Reaction Coordinate ◽  
Acetylene Molecule ◽  
Variational Transition State Theory ◽  
Pressure Limit ◽  
Variational Transition State

Barrierless unimolecular association reactions are prominent in atmospheric and combustion mechanisms but are challenging for both experiment and kinetics theory. A key datum for understanding the pressure dependence of association and dissociation reactions is the high-pressure limit, but this is often available experimentally only by extrapolation. Here we calculate the high-pressure limit for the addition of a chlorine atom to acetylene molecule (Cl + C2H2→C2H2Cl). This reaction has outer and inner transition states in series; the outer transition state is barrierless, and it is necessary to use different theoretical frameworks to treat the two kinds of transition state. Here we study the reaction in the high-pressure limit using multifaceted variable-reaction-coordinate variational transition-state theory (VRC-VTST) at the outer transition state and reaction-path variational transition state theory (RP-VTST) at the inner turning point; then we combine the results with the canonical unified statistical (CUS) theory. The calculations are based on a density functional validated against the W3X-L method, which is based on coupled cluster theory with single, double, and triple excitations and a quasiperturbative treatment of connected quadruple excitations [CCSDT(Q)], and the computed rate constants are in good agreement with some of the experimental results. The chlorovinyl (C2H2Cl) adduct has two isomers that are equilibrium structures of a double-well C≡C–H bending potential. Two procedures are used to calculate the vibrational partition function of chlorovinyl; one treats the two isomers separately and the other solves the anharmonic energy levels of the double well. We use these results to calculate the standard-state free energy and equilibrium constant of the reaction.

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