Premium
Quantifying the non‐RRKM effect in the H + O 2 ⇄ OH + O reaction
Author(s) -
Miller James A.,
Garrett Bruce C.
Publication year - 1997
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/(sici)1097-4601(1997)29:4<275::aid-kin6>3.0.co;2-r
Subject(s) - chemistry , rrkm theory , transition state theory , thermal , thermodynamics , computational chemistry , reaction rate constant , classical mechanics , kinetics , physics
In the present investigation the non‐RRKM behavior in the title reaction is quantified in two different ways: (1) Quasiclassical trajectory calculations of the thermal rate coefficient are compared with results from a microcanonical variational transition‐state theory/RRKM model. Results on both the Varandas DMBE IV and Melius‐Blint potentials indicate that the non‐RRKM behavior acts to reduce the thermal rate coefficient by about a factor of two, independent of temperature from 250 K to 5500 K. The QCT thermal rate coefficients on the two potentials are in remarkably good agreement with experiment and with each other over the entire temperature range. (2) The non‐RRKM behavior as a classical phenomenon is demonstrated and quantified on both potentials by a direct test of the fundamental assumption. Complex‐forming classical trajectories, started as either O + OH or H + O 2 , are shown preferentially to return to the region of configuration space from which they were started. This test is discussed in detail in the text. The transition of the non‐RRKM behavior from classical to quantum mechanics is also discussed. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 275–287, 1997.