Quantum mechanical tunnelling in the processes D + H2 → DH + H and CH4 + H → CH3 + H2. Eckart's tunnelling corrections for rate constants given by ab initio calculations

1979 ◽  
Vol 44 (12) ◽  
pp. 3452-3457 ◽  
Author(s):  
Petr Čársky
Keyword(s):  
Transition State ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Rate Constants ◽  
Transition State Theory ◽  
State Theory ◽  
Quantum Mechanical ◽  
Rate Data ◽  
Dimensional Approach ◽  
One Dimensional

Results of the best reported ab initio calculations are used to evaluate the rate constants of the title processes by means of the transition state theory. The computed rate constants are corrected for the quantum mechanical tunnelling by the Eckart's one-dimensional approach and comparison is made with experimental rate data

Quantum chemical modelling of reactions in hydrocarbon combustion. Study of the CH4 + O2 reactions

1984 ◽  
Vol 49 (6) ◽  
pp. 1440-1447 ◽  
Author(s):  
Ján Urban ◽  
Viliam Klimo ◽  
Jozef Tiňo
Keyword(s):  
Transition State ◽  
Ab Initio ◽  
Rate Constants ◽  
Quantum Chemical ◽  
Transition State Theory ◽  
Saddle Points ◽  
State Theory ◽  
Relative Probability ◽  
Hydrocarbon Combustion ◽  
Chemical Modelling

The rate constants of two alternative reactions, i.e CH4 + O2 → CH2 + H2O2 and CH4 + O2 → CH3 + HOO have been studied by the ab initio and MINDO/3 methods. A preliminary appreciation of the used methods has been done with a selected set of carbene reactions. The characteristics of minima as well as the saddle points on the corresponding reaction paths of both reactions have been found. The discussion of the relative probability of a pathway of the above-mentioned reactions is based on the rate constants determined by the use of transition state theory.

The mechanism and kinetics of the HCO + HONO → HCHO + NO2 reaction — A DFT study

2007 ◽  
Vol 85 (7-8) ◽  
pp. 453-460
Author(s):  
Xiaomin Sun ◽  
Zhengting Cai ◽  
Dachang Feng ◽  
Wenshang Bian ◽  
Qing'an Qiao ◽  
...  
Keyword(s):  
Transition State ◽  
Ab Initio ◽  
Density Function ◽  
Rate Constants ◽  
Transition State Theory ◽  
Transfer Reaction ◽  
Function Theory ◽  
State Theory ◽  
Density Function Theory ◽  
Variational Transition State Theory

The hydrogen-transfer reaction of HCO + HNO2 → HCHO + NO2 has been studied using both the density function theory (DFT) and high-level ab initio method. Three complete reaction paths have been located for the transfer reaction. Geometry optimization and frequency calculation have been performed at the B3LYP/6-311++G** level. QCISD(T) and G3B3 methods have been used to verify the single-point energy. On the basis of the ab initio data, the rate constants have been deduced over a temperature range of 300–3000 K using the transition-state theory and canonical variational transition-state theory with small-curvature tunneling effect. The calculated rate constants have been compared with the previous reported values.Key words: density function theory, reaction mechanism, variational transition-state theory, rate constant.

scholarly journals Ab initio and transition state theory study of the OH + HO2 → H2O + O2(3Σg−)/O2(1Δg) reactions: yield and role of O2(1Δg) in H2O2 decomposition and in combustion of H2

2018 ◽  
Vol 20 (6) ◽  
pp. 4478-4489 ◽  
Author(s):  
M. Monge-Palacios ◽  
S. Mani Sarathy
Keyword(s):  
Transition State ◽  
Ab Initio ◽  
Rate Constants ◽  
Transition State Theory ◽  
Initial Conditions ◽  
Branching Ratio ◽  
State Theory ◽  
H2o2 Decomposition ◽  
P Rate

Rate constants for the reactions OH + HO2 → H2O + O2(3Σg−)/O2(1Δg) have been calculated. The branching ratio to O2(1Δg) is small, and thus particular initial conditions are needed for O2(1Δg) to play a role in combustion.

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