Quasi-classical Trajectory Study Of The Vector Correlations For The Reaction O + HCl â†' HO + Cl

The reaction of O with HCl is of great interest to atmospheric chemistry and serves as a classic example of reaction with heavy-light-heavy dynamics. This reaction attracted a great deal of attention from both experimental and theoretical community. Most of the previous work in reaction dynamics of the title reactions has focused on scalar properties such as the rate constant, cross section, product population distribution, etc. However, complete information on the forces acting in the reaction also requires a consideration of vector properties, as they are key indicators of the anisotropy of the molecular scattering processes. The analysis of the vector properties in molecular reaction also provides a powerful method for characterizing the collision dynamics and potential energy surface. Hence, a true understanding of the gas-phase reaction dynamics is impossible before an integrated consideration of its scalar and vector properties. To gain more dynamic information, in particularly the stereodynamic one, we focus our attention on the calculations of the product rotational polarization for the O(~3P) + HCl reaction and its isotopically substituted reactions on both 3A′′and 3A′PESs. Simultaneously, we expect that the analysis of the vector properties can reveal more detailed characters of the potential energy surface.The calculated results provide a lot of interesting dynamic information: 1, The rotational angular momentum of product OH molecules preferentially aligned along the direction which perpendicular to the relative velocity of reagents, and beside the alignment effect there also orientation effects exists. 2, The reaction O(~3P) + HCl(v=2; j=1,6,9)→OH + Cl is theoretically studied on the benchmark potential energy surface of the ground 3A′′state and the rotational polarization of product OH molecule is very weak and the results can be explained from the van der Waals well in the potential energy surface, and the secondary encounters in the exit channel. 3, The influence of the collision energy and the influence of the reagent rotation and vibration on the vector correlations for reaction O(~3P) + HCl→OH + Cl have been studied. The calculated results indicate that the rotational polarization of product molecule is almost independent of collision energy but sensitive to the reagent rotation and vibration. And the results can be explained by the Impulse Collision Model. 4, Quasi-classical trajectory calculations are also carried out for the O(~3P) + HCl and its isotopic reactions on the benchmark potential energy surfaces for both 3A′′and 3A′symmetries. The results indicate that the product rotational alignment effect calculated on the 3A′surface is stronger than that on the 3A′′surfaces, implies that the effect of the van der Waals minima has significant influence on the product rotational polarization. 5, There are notable variations in product rotational polarization on the 3A′′PES when the H atom is substituted by the D atom, and the discrepancy can be attributed to the indirect reactive mechanism and the mass factor of these two reactions.