Theoretical Study On The Several Microcosmic Reaction Mechanisms And Dynamics Property Of Organosulfur Radical Molecules

Abstract Gas phase sulfur componds motivated at least in part by the emission of sulfur-containing pollutants from the combustion of sulfur-containing fules have significant impact on the environment and biosphere: the acid rain, visibility reduction and climate modification. So the physical and chemistry properties of sulfur componds are cared by many scienties. CH₃S radical is the key intermediate in the process of sulfur componds. There are two aspects about the research of CH₃S, the property of single species and the reaction.In the paper, on the basis of the molecular orbital theory, the tradition state theory as well as quantum chemistry thoery, the several special systems about CH₃S radical have been investigated using Density Functional (DFT) Methods, the Moller-Plesset correlation energy correction MPn, the Atom in Moleculer (AIM) and Natural Bood Orbital (NBO) analysis. The structures of the reactants, products and the transition states along the reaction paths have been obtaind, then obtained the reaction surface, the frequency datum, the thermodynamic datum as well as the information of orbitals. The reaction methanism has been argued deeply using these datum, while we have obtained significative conclusion.The whole paper consists of five chapters. Chaper 1, we investigated the previous studies on CH₃S, CH₂SH and HCS with simple radical in resent years. In chaper 2, the wide application of Quantum Chemistry was summarize, the content of this part is the basis and background of our studies and offer us with useful and reliable quantum methods. Chaper 3, mechanism of isomerizazion reaction and H₂ elimination reaction of CH3S have been studied. In chaper 4 and 5, the mechanism of double radical reaction CH₃S with HCS and ClO are surveyed.The main contents and conclusions in our work are listed as following:1. The isomerizazion reaction of CH₃S—CH₂SH(R1), H₂ elimination reaction of CH₃S→HCS+H₂(R2) and the isomerizazion reaction of HCS→CSH(R3) have been studied at QCISD(t)/6-311++G(d,p)//MPWlPW91/6-311G(d,p) level. The rate constant of the three reaction were obtained by means of small-curvature tunneling correction in the temperature range of 200-2000K. The result revealed that the reaction R1 is the dominant reaction channel; CH3S radical is more stable than CH₂SH in low temperature...