Angular momentum conservation in the O + OH ? O2 + H reaction

Abstract

We have studied the O + OH O2 + H reaction on Varandas's DMBE IV potential using a variety of statistical methods, all involving the RRKM assumption for the HO2* complex. Comparing our results using microcanonical variational transition-state theory (μVT) with those using microcanonical/fixed-J variational transition-state theory (μVT-J), we find that the effect of angular momentum conservation on the rate coefficient is imperceptible up to a temperature of about 700 K. Above 700 K angular momentum conservation increasingly reduces the rate coefficient, but only by approximately 21% even at 5000 K. Comparing our μVT-J calculations with the quasi-classical trajectory (QCT) results of Miller and Garrett [1], we confirm their conclusion that non-RRKM dynamics of the HO2* complex reduces the rate coefficient by about a factor of 2 independent of temperature. Our calculations of k(c), the rate coefficient for HO2* formation from O + OH, are in excellent agreement with the QCT results of Miller and Garrett. Although the differences are not large, we find kCVT(c) > kμVT(c) > kμVT-J(c) > kQCT(c), where CVT stands for canonical variational transition-state theory. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 753–756, 1999