Journal of Physical Chemistry A, Vol.102, No.25, 4899-4910, 1998
Dual-level direct dynamics calculations of the reaction rates for a Jahn-Teller reaction : Hydrogen abstraction from CH4 or CD4 by O(P-3)
We report calculations of the reaction rates of O(P-3) + CH4 --> OH + CH3 and O(P-3) + CD4 --> OD + CD3 over the temperature range 300-2500 K. The calculations are based on variational transition state theory in curvilinear coordinates with transmission coefficients calculated by the microcanonical optimized multidimensional tunneling approximation. A dual-level algorithm is used for the dynamical calculations. The higher level is UMP2/cc-pVTZ, and two lower levels are employed : PM3-SRP and an analytical potential energy surface. Using the canonical unified statistical model with microcanonical optimized multidimensional tunneling contributions, we obtain good agreement with experimental rate constants.
Keywords:TRANSITION-STATE THEORY;POTENTIAL-ENERGY SURFACES;CHEMICAL-REACTION RATES;PLESSET PERTURBATION-THEORY;REACTION-PATH DYNAMICS;SEMICLASSICAL TUNNELING CALCULATIONS;ELECTRONIC-STRUCTURE CALCULATIONS;CLASSICAL MECHANICAL THEORY;MOLECULAR-ORBITAL THEORY;COUPLED-CLUSTER SINGLES