Theoretical Study Of The Stereodynamics Of The Reactions Of O ⁺+H₂ And Its Isotopic Variants

During the past decades, molecular reaction dynamics has made great progress and has gotten into a new stage of the state-to-state chemical dynamics. Formerly, the theoretical and experimental study of the atomic and molecular collision reaction always focused on some scalar properties. With the rapid development of experimental techniques, however, the interest in vector properties of chemical reactions has increased significantly in recent decades. Only by understanding the scalar and vector properties together, can we obtain the fullest picture of the scattering dynamics. Quasiclassical Trajectory Calculation (QCT) is one of the effective methods for investigating atomic and molecular collision reaction stereodynamics.Due to the atmospheric abundance of oxygenated compounds, reactions involving atomic oxygen either as reactant or as product, are exceedingly important. Because of its relatively simple electronic structure, the O⁺+HH system has been considered as one of the model systems for reactions and consequently studied widely. The extensive studies can help us to study other reactions.The scalar properties and vector properties of the reactions of O⁺+HH and its reverse have been studied using the (QCT) method in this paper. The development of the molecular reaction dynamics and stereodynamics and their present situation are presented in section one. In Section two, the related theories of QCT and the vector correlations are introduced.In Section three, the chemical reaction O⁺+H₂ and its isotopic variants at the collision energy of 20 kcal /mol have been carried out by using the quasi-classical trajectory (QCT) method on RODRIGO surface. The correlated k-j′, k-k′-j′angular distributions, polarization dependent differential cross sections (PDDCSs) and the product rotational alignment are discussed in detail. The calculations indicate that the stereodynamics properties of the reactions of O⁺+H₂→OH⁺+H,O⁺+DH→OD⁺+H and O⁺+TH→OT++H are sensitive to the mass factor and the repulsive energy of diatomic molecule.In Section four, O⁺+DH(v=0,j=0)→OD⁺+H reactions on the RODRIGO potential energy surface have been carried out to study the isotope effect on stereo-dynamics at the collision energies of 1.0eV,1.5eV,2.0eV and 2.5eV. The distributions of dihedral angle P(φ_r) and the distributions of angle between k and j′, P(θ_r) are discussed. Furthermore, the angular distributions of the product rotational vectors in the form of polar plot inθ_r andφ_rare calculated. The differential cross section (DCS) shows interesting phenomenon that the reaction is dominated by the direct reaction mechanism. The reaction probability and the reaction cross section are also calculated in this paper. The results indicate that the stereo-dynamics properties of the title reactions are sensitive to the collision energy.In Section five, We study the dynamic stereochemistry of the O⁺+DH (v=0,1,2,3,j=0)→OD⁺+H reactions. Results indicate that the reagent's vibrational excitation has a considerable influence on the distribution of the k-j′, k-k′correlation and the k-k′-j′correlation. In addition, The reaction probability and the reaction cross section are found to be sensitive to the vibrational quantum number.