scholarly journals Hydrogen tunnelling in the rearrangements of carbenes: the role of dynamical calculations

2020 ◽  
Vol 22 (3) ◽  
pp. 962-965 ◽  
Author(s):  
Timothy A. H. Burd ◽  
Xiao Shan ◽  
David C. Clary
Keyword(s):  
Transition State ◽  
Transition State Theory ◽  
State Theory

A tunnelling controlled reaction is studied with semiclassical transition state theory, rationalising the results of experiment.

scholarly journals Kinetic Analysis of the Effect of Poliovirus Receptor on Viral Uncoating: the Receptor as a Catalyst

2001 ◽  
Vol 75 (11) ◽  
pp. 4984-4989 ◽  
Author(s):  
Simon K. Tsang ◽  
Brian M. McDermott ◽  
Vincent R. Racaniello ◽  
James M. Hogle
Keyword(s):  
Activation Energy ◽  
Transition State ◽  
Kinetic Analysis ◽  
Transition State Theory ◽  
State Theory ◽  
Viral Receptor ◽  
Poliovirus Receptor ◽  
Entropic Stabilization ◽  
Entropic Effects

ABSTRACT We examined the role of soluble poliovirus receptor on the transition of native poliovirus (160S or N particle) to an infectious intermediate (135S or A particle). The viral receptor behaves as a classic transition state theory catalyst, facilitating the N-to-A conversion by lowering the activation energy for the process by 50 kcal/mol. In contrast to earlier studies which demonstrated that capsid-binding drugs inhibit thermally mediated N-to-A conversion through entropic stabilization alone, capsid-binding drugs are shown to inhibit receptor-mediated N-to-A conversion through a combination of enthalpic and entropic effects.

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.

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.

Quasiclassical Trajectory and Transition State Theory Studies of the N(4S) + H2↔ NH(X3Σ-) + H Reaction

2002 ◽  
Vol 106 (16) ◽  
pp. 4125-4136 ◽  
Author(s):  
Ronald Z. Pascual ◽  
George C. Schatz ◽  
Gÿorgÿ Lendvay ◽  
Diego Troya
Keyword(s):  
Transition State ◽  
Transition State Theory ◽  
State Theory
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