NOTE ON THE SIMPLE COLLISION THEORY OF BIMOLECULAR REACTIONS

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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Space–time histories approach to fast stochastic simulation of bimolecular reactions

The Journal of Chemical Physics ◽

10.1063/5.0037266 ◽

2021 ◽

Vol 154 (16) ◽

pp. 164111

Author(s):

Thorsten Prüstel ◽

Martin Meier-Schellersheim

Keyword(s):

Stochastic Simulation ◽

Space Time ◽

Bimolecular Reactions ◽

Time Histories

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Perspective: Vibrational-induced steric effects in bimolecular reactions

The Journal of Chemical Physics ◽

10.1063/1.4913323 ◽

2015 ◽

Vol 142 (8) ◽

pp. 080901 ◽

Cited By ~ 39

Author(s):

Kopin Liu

Keyword(s):

Steric Effects ◽

Bimolecular Reactions

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PLATELET AGGREGATION DOES NOT CONFORM TO SIMPLE PARTICLE COLLISION THEORY

10.1055/s-0038-1644550 ◽

1987 ◽

Author(s):

Moideen P Jamaluddin

Keyword(s):

Platelet Aggregation ◽

Rate Equation ◽

Rate Constants ◽

Kinetic Scheme ◽

Order Type ◽

Second Order ◽

Particle Collision ◽

Collision Theory ◽

Rate Law ◽

First Order

Platelet aggregation kinetics, according to the particle collision theory, generally assumed to apply, ought to conform to a second order type of rate law. But published data on the time-course of ADP-induced single platelet recruitment into aggregates were found not to do so and to lead to abnormal second order rate constants much larger than even their theoretical upper bounds. The data were, instead, found to fit a first order type of rate law rather well with rate constants in the range of 0.04 - 0.27 s-1. These results were confirmed in our laboratory employing gelfiltered calf platelets. Thus a mechanism much more complex than hithertofore recognized, is operative. The following kinetic scheme was formulated on the basis of information gleaned from the literature.where P is the nonaggregable, discoid platelet, A the agonist, P* an aggregable platelet form with membranous protrusions, and P** another aggregable platelet form with pseudopods. Taking into account the relative magnitudes of the k*s and assuming aggregation to be driven by hydrophobic interaction between complementary surfaces of P* and P** species, a rate equation was derived for aggregation. The kinetic scheme and the rate equation could account for the apparent first order rate law and other empirical observations in the literature.

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