scholarly journals A fallacy in some interpretations of the quasi-thermodynamics of reaction kinetics

1984 ◽  
Vol 37 (4) ◽  
pp. 867 ◽  
Author(s):  
SD Hamann
Keyword(s):  
Transition State ◽  
Reaction Kinetics ◽  
Transition State Theory ◽  
State Theory

The fact that experimentally determined 'volumes of activation' and 'entropies of activation' obey a relationship that is formally similar to one of Maxwell's thermodynamic relations is a mathematicalconsequence of the definitions of those quantities. Contrary to suggestions in the literature, it provides no evidence in support of the quasi-thermodynamic and equilibrium assumptions of the transition state theory.

Reaction Kinetics of CO + HO2→ Products:  Ab Initio Transition State Theory Study with Master Equation Modeling†

2007 ◽  
Vol 111 (19) ◽  
pp. 4031-4042 ◽  
Author(s):  
Xiaoqing You ◽  
Hai Wang ◽  
Elke Goos ◽  
Chih-Jen Sung ◽  
Stephen J. Klippenstein
Keyword(s):  
Transition State ◽  
Ab Initio ◽  
Master Equation ◽  
Reaction Kinetics ◽  
Transition State Theory ◽  
State Theory ◽  
Equation Modeling ◽  
Kinetics Of

scholarly journals Atmospheric oxidation reactions of imidazole initiated by hydroxyl radicals: kinetics and mechanism of reactions and atmospheric implications

2019 ◽  
Vol 21 (16) ◽  
pp. 8445-8456 ◽  
Author(s):  
Zahra Safaei ◽  
Abolfazl Shiroudi ◽  
Ehsan Zahedi ◽  
Mika Sillanpää
Keyword(s):  
Quantum Chemistry ◽  
Transition State ◽  
Reaction Kinetics ◽  
Hydroxyl Radicals ◽  
Transition State Theory ◽  
Oxidation Mechanism ◽  
State Theory ◽  
Atmospheric Oxidation ◽  
Oxidation Reactions ◽  
Quantum Chemistry Calculations

The atmospheric oxidation mechanism of imidazole initiated by hydroxyl radicals is investigated via OH-addition and H-abstraction pathways by quantum chemistry calculations at the M06-2X/aug-cc-pVTZ level of theory coupled with reaction kinetics calculations using statistical Rice–Ramsperger–Kassel–Marcus (RRKM) theory and transition state theory (TST).

Microscopic Interpretation of Arrhenius Parameters

2018 ◽  
Author(s):  
Niels Engholm Henriksen ◽  
Flemming Yssing Hansen
Keyword(s):  
Activation Energy ◽  
Transition State ◽  
Transition State Theory ◽  
Average Energy ◽  
Zero Point ◽  
State Theory ◽  
Exponential Factor ◽  
Quantum Tunnelling ◽  
Microscopic Interpretation ◽  
The Difference

This chapter reviews the microscopic interpretation of the pre-exponential factor and the activation energy in rate constant expressions of the Arrhenius form. The pre-exponential factor of apparent unimolecular reactions is, roughly, expected to be of the order of a vibrational frequency, whereas the pre-exponential factor of bimolecular reactions, roughly, is related to the number of collisions per unit time and per unit volume. The activation energy of an elementary reaction can be interpreted as the average energy of the molecules that react minus the average energy of the reactants. Specializing to conventional transition-state theory, the activation energy is related to the classical barrier height of the potential energy surface plus the difference in zero-point energies and average internal energies between the activated complex and the reactants. When quantum tunnelling is included in transition-state theory, the activation energy is reduced, compared to the interpretation given in conventional transition-state theory.

Bimolecular Reactions, Transition-State Theory

2018 ◽  
Author(s):  
Niels Engholm Henriksen ◽  
Flemming Yssing Hansen
Keyword(s):  
Transition State ◽  
Saddle Point ◽  
Transition State Theory ◽  
Classical Mechanics ◽  
Small Degree ◽  
State Theory ◽  
Reaction Coordinate ◽  
Partition Functions ◽  
Bimolecular Reactions ◽  
Activated Complex

This chapter discusses an approximate approach—transition-state theory—to the calculation of rate constants for bimolecular reactions. A reaction coordinate is identified from a normal-mode coordinate analysis of the activated complex, that is, the supermolecule on the saddle-point of the potential energy surface. Motion along this coordinate is treated by classical mechanics and recrossings of the saddle point from the product to the reactant side are neglected, leading to the result of conventional transition-state theory expressed in terms of relevant partition functions. Various alternative derivations are presented. Corrections that incorporate quantum mechanical tunnelling along the reaction coordinate are described. Tunnelling through an Eckart barrier is discussed and the approximate Wigner tunnelling correction factor is derived in the limit of a small degree of tunnelling. It concludes with applications of transition-state theory to, for example, the F + H2 reaction, and comparisons with results based on quasi-classical mechanics as well as exact quantum mechanics.

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