Theoretical Investigation On The Dynamics Of Several Atomic-diatomic Reaction Systems

The relevant dynamical information of an elementary chemical reaction can be obtained from the investigation on the micro process of atomic and molecular reactions, and thus it does contribute to a better understanding of the collision mechanism. For an elementary chemical reaction, we should not only study its scalar properties, such as integral reaction cross sections, reaction probability, the rate constants, but also its vector properties, such as the product rotational angular momentum distributions and the vector correlations between the reactants and products. Therefore, a fully dynamical picture of chemical reaction can be given by combining the above two properties.In our thesis, the quasi-classical trajectory method have been used to study the scalar and vector properties of the C+CH→CC+H, H+Li F→HF+Li and H+Br O→HBr+O reactions. The main conclusions are summarized as follows:(1) The C+CH→CC+H reaction is a no threshold reaction. When the temperature T=150-500 K, the rate constants of reaction have shown large difference, and also indicated a greater change influenced by the vibrational quantum states. However, it is insensitive to the change of rotational state. The results of the product scattering distribution have illustrated strongly forward and backward scattering with the change of vibrational and rotational states. Meanwhile, as vibrational state increases, the alignment of the product rotational angular momentum j’ enhances, but it is weakened as the increase of the rotational state. When the H atom of the reactant is replaced by the D atom, the scalar and vector properties of the atom are both shown strong isotopic effects.(2)When the temperature T>400K, the rate constant of H+Li F→HF+Li reaction began to increase. Under the same collision energy condition, the total integral reaction cross sections, the rate constants and the product alignment get larger with the increase of the vibrational state. Meanwhile, they are all insensitive to the change of the rotational state. It also indicated that the isotopic substitution had great effect on the product scattering distributions which the forward scattering of the product had increased and the scattering peak had moved to the left.(3)When T<150K, the rate constants of H+Br O→HBr+O reaction changed greatly. As vibrational state increases, the reaction probability, integral cross sections and rate constants demonstrate decreasing trend. And the alignment of the product rotational angular momentum j’ is weakened as well. Meanwhile, as vibrational state changes, the product scattering shows forward scattering while it scatters forward and backward when the rotational state changes. It was also found that the isotopic substitution had greatly influenced the dynamical information such as the rate constants and the angular distributions of the product.Besides, by using the quantum mechanical and quasi-classical methods, we have studied the integral cross section of F+HD→DF+H reaction. With the increase of the collision energy, the results of the integral cross section obtained by the above two methods indicates the same increasing trend. Meanwhile, we have investigated the state-to-state differential cross section. It shows that our theoretical results are in agreement with the experimental findings. With increasing of the product vibrational states, the product scattering distribution have gradually transferred from the back scattering to the sideward scattering.