Theoretical Study Of The Dynamics For The System NH₂

Elements hydrogen and oxygen widely exists in the compound of the nature,chemical reaction which is formed by the NH2system containing the elementshydrogen and oxygen plays an important role not only in combustion chemistry andatmospheric chemistry, but also has important applications in catalysis and resources.Up to now, there is almost no study on the stereo-dynamic information of isotopiceffect of H(4S)+NH reaction. We have studied the dynamics properties of the NH2system performed quasi-classical trajectory (QCT) studies based on the potentialenergy surface (PES) which constructed by Zhai Hongsheng and Han Keli. We haveinvestigated the influences of collision energy and isotopic on the stereo-dynamicsproperties of the H+NH reaction, as well as the collision energy on the dynamicsproperties of the N+H2reaction. In the exit valley of the PES the reactant releaseenergy, therefore it is a reject PES and the reaction is dominated by the direct reactionmechanism. We proposed an overall and reasonable explanation through the analysis ofcalculation results and the topology characteristics of the PES.Firstly, we studied influence of isotopic effect on the stereo-dynamics of positivereaction to the system to change attack atoms. The results of the study show that, theproduct molecules have backward scattering with three isotopic reaction. Rotationalangular momentum vector contain product of molecular alignment and orientationeffect. We found that the isotope effect is more obvious.In addition, we investigated influence of collision energy and isotopic effect on thedynamics of positive reaction to the system to change target molecule. It has beenfound, the product molecules have backward scattering with three isotopic reaction.The scattering degree decreases with the increase of collision energy. The reactioncross sections were gradually increased with the increase of collision energy. In thesame collision energy, the backward scattering enhancement product molecules withthe increase of molecular weight of the target. The molecular rotational angularmomentum is more sensitive to the collision energy decreased. We also found that theisotopic substitution does not change the reaction mechanism.Finally, we studied the properties on the dynamics of reverse reaction to thesystem with collision energy35kcal/mol to70kcal/mol. The result illustrates that the increase of molecular backward scattering degree gradually increased with thecollision energy. Molecular orientation and orientation degree are influenced of theproduct rotational angular momentum vector by the initial collision energy. With theincrease of the collision energy, the integral reaction cross section increases, it isincreased of the reactant rotational excitation, and the molecular rotational angularmomentum orientation and orientation degree increased and decreased respectively.We found some interesting phenomenon and conclusions in the process of studyand given reasonable explanations of them. The study enriches the theory of thestereo-dynamics on this reaction.