| Transient species generally exist in many chemical reactions. They play an important role in combustion chemistry, atmospheric chemistry and chemical laser, etc. Because of their short lives, high reactive activities and the difficulty of getting the pure species, the experimental research for their structures and reaction features (especially the reaction mechanisms and the dynamics) is very difficult.F atom is just one of these species. Because of its high reaction activity, it can easily abstract H atom from small molecules, such as CH4, HiO, CHsOH, etc. These hydrogen abstraction reactions are elementary reactions in combustion and atmospheric process. These reactions can also produce important oxide intermediates and vibrationally excited HF molecule. So detailed research of hydrogen abstraction mechanism and dynamic property is significant. In recent years, people found that F atom can penetrate into the silicon surface so as to influence properties of silicon-containing species. Then it's necessary to research reactions between F atom and silicon-containing species in order to improve the quality of the crystalline and amorphous silicon films. At the same time, F+SiFU reaction can produce SiF, which is needed in spectrum research, both theoretically and experimentally.The developments of computer technologies, quantum chemistry calculation methods and various dynamic theories provide us a new way to study the transient species and their dynamic properties. Quantum chemistry calculation methods, which is based on electronic structure theory, can provide us precise information of molecule structure and energy, etc. Direct dynamic calculation methods, which is based on variational transition state theory, provide us a way to perform direct dynamic calculations by using the results derived from quantum chemistry calculation. In our work, we scanned the potential energy surfaces, optimized the stationary points in reaction paths, and completed internal reaction coordination calculation to get minimum energy path(MEP), by using the MP2 method and high level basis set in Gaussian94 quantum chemistry program package. Then we collected the data of the stationary points and interpolate points, performed direct dynamic calculation for aseries of hydrogen abstraction reactions, by using conventional transition state theory and variational transition state theory adding up minimum-energy-path semiclassical adiabatic ground-state (MEPSAG) tunneling effect or small-curvature semiclassical adiabatic ground-state (SCSAG) tunneling effect correction in Polyrate7.8 program. We gained a series of accurate dynamic data theoretically in a large range of temperature.We designed our research route as follows: The first step, we choose F+CH4, F+H2O as reaction systems to carry out our calculation of hydrogen abstraction, because carbon atom and oxygen atom have different affinities. The second step, we choose F+SiH4, F+SiHsF and F+SiHsCl as reaction systems. The third step, we choose F+CHsOH reaction as reaction system.The main conclusions in our work are:1. The transition state of F+CH4 should have C3v symmetry on the level of UMP2/6-311++g(3df,2p) basis set. The reaction rate constant of F+CH4 is 3.24 x10-11cm3-molecule-1-sec-1, which agrees well with experimental data. At low temperature, the F+H2O reaction has great tunneling effect. The former complex and the latter complex of the two reactions are located.The rate constant of F+CH4 is bigger than that of F+HiO, because F+CH4 reaction has a barrier of 7.80 kJ/mol, which is lower than that of F+H2O, 39.03 kJ/mol.2. The results, which are gained on the level of UMP2(full)/6-311++g(d,p) (6-311++g(2df,2p) basis set for Si, F and Cl) basis set, show the barrier of F+SiH4, F+SiH3F and F+SiH3Cl is 1.02 kJ/mol, 3.54 kJ/mol and 1.45 kJ/mol respectively. The reaction rate constant of F+SiHsF is the biggest and that of F+SiHsCl is the smallest. We believe that electronic effect of F atom, Cl atom, number of hydrogen atom, and steric hindrance wi...
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