Angular momentum conservation in the O+OH <-> O-2+H reaction

We have studied the O + OH <-> O-2 + H reaction on Varandas's DMBE IV poten tial using a variety of statistical methods, all involving the RRKM assumpt ion for the HO2* complex. Comparing our results using microcanonical variat ional transition-state theory (mu VT) with those using microcanonical/fixed -J variational transition-state theory (mu VT-J), we find that the effect o f 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% e ven at 5000 K. Comparing our mu VT-J calculations with the quasi-classical trajectory (QCT) results of Miller and Garrett [1], we confirm their conclu sion that non-RRKM dynamics of the HO2* complex reduces the rate coefficien t 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 differe nces are not large, we find k(CVT)((c)) > k(mu VT)((c)) > k(mu VT-J)((c)) > k(QCT)((c)), where CVT stands for canonical variational transition-state t heory. (C) 1999 John Wiley & Sons, Inc.