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

摘要

Three-dimensional quantum mechanical calculations have been carried out, using a modification of the log-derivative version of Kohn's variational 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 states. Analysis of the bound states close to the dissociation threshold have revealed that HO2 is a mainly irregular system and in this paper 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 magnitude. 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 the predictions of random matrix theory, and are found to be in fair agreement. The Rampsberger-Rice-Kassel-Marcus (RRKM) rates, calculated using variational transition state theory, compare well to the average of the quantum mechanical rates. The vibrational/rotational state distributions of O-2 show strong fluctuations in the same way as the dissociation rates. However, their averages do not-agree well with the predictions 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 quantum calculations. (C) 1996 American Institute of Physics. [References: 89]