Quasiclassical trajectory (and variational transition state theory) study of the rates and temperature-dependent activation energies of the reactions Mu+H2 (completely thermal) and H, D, and Mu+H2 (v=0, j=2)

Abstract

We report forward and backward quasiclassical trajectory calculations of the rate constant for the reaction Mu+H2→MuH+H at 444–2400 K. The accuracy of the calculations is assessed by comparison to variational transition state theory, both with and without tunneling contributions, and to experiment. We find the backward trajectory calculations are more accurate, as would be expected since the dynamical bottleneck occurs towards the products in the Mu+H2 reaction. Both the reverse trajectory calculations and the variational transition state theory calculations including tunneling agree with the experimental rate constants within a factor of about 2, which is considered very good agreement. We also report trajectory calculations and variational transition state theory calculations for the temperature-dependent activation energy, which increases by about 4 kcal/mol over the temperature range studied. To aid in the interpretation of this temperature dependence and that found in previous studies for H+H2 and D+H2, we also report temperature-dependent activation energies for the three state-selected rate constants H(D,Mu)+H2(v=0, j=2) →H2(HD,HMu)+H.