THEORETICAL-STUDY OF THE UNIMOLECULAR DISSOCIATION HO2-]H-2 .2. CALCULATION OF RESONANT STATES, DISSOCIATION RATES, AND O-2 PRODUCT STATE DISTRIBUTIONS(O)

Three-dimensional quantum mechanical calculations have been carried ou t, using a modification of the log-derivative version of Kohn's variat ional principle, to study the dissociation of HO2 into H and O-2. In a previous paper, over 360 bound states were found for each parity, and these are shown to extend into the continuum, forming many resonant s tates. Analysis of the bound states close to the dissociation threshol d have revealed that HO2 is a mainly irregular system and in this pape r it is demonstrated how this irregularity persists in the continuum. At low energies above the threshold, these resonances are isolated and have widths that fluctuate strongly over more than two orders of magn itude. At higher energies, the resonances begin to overlap, while the fluctuations in the widths decrease. The fluctuations in the lifetimes and the intensities in an absorption-type spectrum are compared to th e predictions of random matrix theory, and are found to be in fair agr eement. The Rampsberger-Rice-Kassel-Marcus (RRKM) rates, calculated us ing variational transition state theory, compare well to the average o f the quantum mechanical rates. The vibrational/rotational state distr ibutions of O-2 show strong fluctuations in the same way as the dissoc iation rates. However, their averages do not-agree well with the predi ctions of statistical models, neither phase space theory (PST) nor the statistical adiabatic channel model (SACM), as these are dependent on the dynamical features of the exit channel. The results of classical trajectory calculations agree well on average with those of the quantu m calculations. (C) 1996 American Institute of Physics.