Threehyphen;body recombination and dissociation rate coefficients (krandkd, respectively) for the reactionsH2plus;Hrlarr2;Hplus;Hplus;Hhave been evaluated for temperatures ranging between 300 and 10 000deg;K on the basis of the modified phasehyphen;space theory of reaction rates and Monte Carlo trajectory calculations. The semiempirical Porterhyphen;Karplus surface for H3was used in the calculations. Good agreement was obtained between the theoretical estimates ofkdand the bulk of the dissociation rate measurements. However, in contradistinction to some of the recent experimental investigations, neither the extremely steep temperature decaylpar;inverted lazy s Tminus;6rpar;ofkrat high temperatures nor the existence of a pronounced maximum inkrat moderate temperatures are supported by this theoretical work. Possible reasons for these differences are suggested. A simple ratio was deduced which relateskrlpar;Hrpar;and the corresponding rate coefficients of the isotopes of hydrogen. The result is in good agreement with available experimental measurements and enables one to predict the latter rate coefficients without additional trajectory calculations. An example is given to illustrate the capability of the present Monte Carlo method in obtaining other useful information about atomic and molecular collision processes.
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