Theoretical calculations were carried out on the H-atom abstraction reaction from methane by XO (X = F, Cl or Br) radicals attack. Geometry optimizations and vibrational frequency calculations were performed using three methods: Moller-Plesset second-order perturbation theory (MP2), quadratic configuration interaction in the space of single and double excitations (QCISD), and the hybrid three-parameter exchange functional with Becke's non local exchange and Lee-Yang-Parr correlation functional (B3LYP). Single-point energy calculations were performed using several high quality basis sets. Canonical transition-state theory was used to perdict the rate constants as a function of temperature (700 - 2500K), and three-parameter Arrhenius expressions were obtained by fitting to the computed rate constants. The possible impact of the title reactions in combustion chemistry is also discussed.
Citation: Journal of Physical Chemistry A
Issue: No. 17
Pub Type: Journals
ab Initio, Arrhenius, Kinetics, rate constant