【作者】 牛古丹；

【导师】 刘波； 徐雅琴；

【作者基本信息】 哈尔滨理工大学 ， 材料工程， 2007， 硕士

【摘要】 本文应用直接动力学方法，对Br+CH₃SOCH₃→products反应的微观机理和速率常数进行了理论研究。利用GAUSSIAN03程序，在BH&HLYP／6-311G（2d，2p）水平下计算了稳定点（反应物、氢键络合物、过渡态和产物）的几何构型和振动频率，进一步利用内禀反应坐标理论获得反应的最小能量路径，在最小能量路径上选点进行QCISD（T）高水平单点能量校正。然后结合POLYRATE9.1程序，使用变分过渡态理论计算了该化学反应的速率常数。获得了该反应的势能面信息，包括稳定物的几何构型、反应路径、反应势垒、反应焓等，进一步利用变分过渡态理论方法得到上述反应的速率常数。理论结果与实验符合得非常好，进一步验证了理论结果的可靠性，并对实验尚未能测定的温度范围，给出了可靠的理论预测。Br+CH₃SOCH₃反应有两个反应通道，在200—2000 K温度范围内，两个反应通道分支比的计算可以看出生成HBr的反应通道R1与生成CH₃的反应通道R2存在着竞争，反应通道R1是主要的反应通道，而生成CH₃的反应通道R2始终是次要反应。在所研究的温度范围内，变分效应和小曲率隧道效应对反应速率常数的计算影响都很小。更多还原

【Abstract】 In this thesis, the direct dynamics methods have been use to study the microcosmic mechanism and rate constants of the reactions: Br+CH₃SOCH₃ products.By means of Gaussian03 program, the geometries and frequencies of the stationary points （reactant, hydrogen bond complex, transition state, and products） are calculated at the BH&HLYP/6-311G（2d,2p） level. The minimum energy path （MEP） is calculated at the same level by intrinsic reaction coordinate （IRC） theory. Furthermore, with the selected points along the MEP. In order to gain more accurate energy profile, the energies of the selected points on the MEP are refined at MC-QCISD level. Finally, the canonical variational transition state theory with small-curvature tunneling correction are applied to obtain the reaction rate constants by using POLYRATE-Version 9.1 program.For the reactions mentioned above, the potential surface information is obtained, including geometries, energies, gradients, and force constants matrices of the stationary points （reactants, transition states and products）, some extra points along the minimum energy path （MEP）, the reaction enthalpies(△^H₂₉₈0) and potential barriers（△E） with zero-point energy correction（ZPE）. Subsequently, the rate constants of the above-mentioned reactions are calculated using the variational transition state theory （VTST）. The theoretical results obtained are in good agreement with the experimental values. It indicates that the present calculations can provide reliable prediction of the rate constants for the above-mentioned reactions at higher temperatures.The reaction Br + CH₃SOCH₃ has two alternative reaction pathways, i. e., the HBr and CH₃ forming channels. From the calculation the branching ratios of the temperature dependence, it can be seen that two reaction channels is competitive reaction. The rate constant for the reaction channel to yield HBr is the major channel. The reaction channel to yield CH₃ is minor channel over the whole temperature region 200—2000 K. Both the variational effect and the tunneling effect are small over the whole temperature region.更多还原