Quasiclassical trajectory study of the reaction O(³P) + HCl → OH + Cl. The effects of vibrational excitation, rotational excitation, and isotopic substitution on the dynamics

Three dimensional quasiclassical trajectory calculations were carried out for the nearly thermoneutral reaction of oxygen atoms O(³P) with hydrogen chloride molecules (HCl and DCl), for reaction temperatures of 300 and 700 K, employing two LEPS potential energy surfaces. Calculations for 300 K were performed for various initial vibrational states of the reagents HCl(ν = 0, 1, 2, and 4) and DCl(ν = 0 and 1). Calculations for 700 K were carried out for the ground vibrational state ν = 0. The effect of rotational excitation on reactivity was investigated by calculating reaction cross sections for specific initial rotational states for the reaction O + HCl(ν = 0, J = 0-19) for collision energies of 6.0 and 10.0 kcal/mol. The rate of the O + HCl reaction was found to be enhanced by more than two orders of magnitude (factors of 150 and 390 for the two surfaces used) for O + HCl(ν = 1), and by more than three orders of magnitude for O + HCl(ν = 2), as compared to O + HCl(ν = 0). The influence of rotational excitation on reactivity was found to be very different for the two surfaces used, and a possible explanation is suggested. The results of the trajectory calculations are compared with experimental results of rate constants and kinetic isotope effects and with results of other trajectory calculations for this system.