QUANTUM-MECHANICAL CALCULATIONS OF THE RATE-CONSTANT FOR THE H-2-]H+H2O REACTION - FULL-DIMENSIONAL RESULTS AND COMPARISON TO REDUCED DIMENSIONALITY MODELS(OH)

The cumulative reaction probability is calculated for the H-2+ OH-->HH2O reaction in its full (six) dimensionality for total angular moment um J=0. The calculation, which should give the (numerically) exact res ult for the assumed potential energy surface, yields the cumulative re action probability directly, without having to solve the complete stat e-to-state reactive scattering problem. Higher angular momenta (J>0) w ere taken into account approximately to obtain the thermal rate consta nt k(T) over the range 300 degrees<T<700 degrees. The result deviates significantly from the experimental rate constant, suggesting that the potential energy surface needs to be improved. A systematic series of reduced dimensionality calculations is carried out in order to charac terize the behavior and reliability of these more approximate treatmen ts; a comparison of the full dimensional results with previous reduced dimensionality calculations is also made.