Journal of Chemical Physics, Vol.100, No.4, 2697-2706, 1994
Accurate Quantum Calculations for H-2+oh-)H2O+h - Reaction Probabilities, Cross-Sections, and Rate Constants
Following a previous Communication [J. Chem. Phys. 99, 5615 (1993)], which reported several initial state-selected total reaction probabilities for the title reaction for J = 0, we present in this paper the methodologies of the previous calculation and show results of new calculations. In particular, the present calculations are extended to ah angular momentum J > 0 and obtained reaction cross sections for a range of energies using the centrifugal sudden (CS) approximation. The competed cross sections are used to obtain the state-specific thermal rate constants for both the ground and the excited vibrations of HZ The dynamics calculation, in which the nonreactive OH bond is frozen, includes explicitly five degrees of freedom in the time-dependent quantum dynamics treatment. The comparison of the present accurate cross sections with other approximate theoretical calculations shows discrepancies. The computed rate constants (from the ground rotation state) are larger than experimental measurements at low temperatures, the v = 0 rate is larger than the corresponding experimental rate by a factor of 1.8, and the ratio of v = 1 to v = 0 rate is a factor of 4.8 greater than the experimental ratio at 300 K. The calculated reaction rates are also compared to those of other theoretical calculations and the differences are discussed in the text.
Keywords:KOHN VARIATIONAL PRINCIPLE;POTENTIAL-ENERGY SURFACE;BOND-SELECTED REACTION;WAVE PACKET CALCULATION;S-MATRIX VERSION;3-DIMENSIONAL QUANTUM;VIBRATIONAL PREDISSOCIATION;CONVERGED QUANTUM;PHOTODETACHMENT SPECTRUM;SCATTERING CALCULATIONS