Quantifying the non-RRKM effect in the H + O2 ⇄ OH + O reaction

✍ Scribed by James A. Miller; Bruce C. Garrett

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 178 KB
• Volume: 29
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/(sici)1097-4601(1997)29:4<275::aid-kin6>3.0.co;2-r

✦ Synopsis

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 ϩ OH or H ϩ 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.