自由基反应的理论研究

【作者】 王鹤峰；

【导师】 文振翼； 王尧宇；

【作者基本信息】 西北大学 ， 无机化学， 2001， 硕士

【摘要】 本文主要包括四方面的工作：六氯苯环与OH自由基的反应动力学计算，Criegee自由基反应的动力学计算，C₂H₂的反应速率计算，优化程序SIMPLEX的改进。 六氯苯环（HCB）是一种易挥发，有毒的物质，不易与其他物质反应，从而能长期存在于大气中。HCB与大气中自由基的反应对我们了解它在大气中的迁移，滞留和降解是很有意义的。我们通过理论计算，分别用AM1和DFT方法进行了该反应的热力学和动力学的研究。 Criegee中间体以被认为是大气中一些重要污染物的来源，是引发大量次级反应的关键物质，但由于Criegee中间体寿命短，对其可能参与的一些大气化学反应进行实验研究有一定难度，因此我们对Criegee自由基的反应进行了理论研究。 一个足够精确的势能面可以提供化学反应的所有信息，从势能面的一个谷口（反应物）到另一个谷口（产物）的能量最小曲线（MEP）构成了反应路径。由所得的反应路径曲线，应用变分过渡态理论就可以算出反应速率常数。我们计算了C₂H₂的一些反应的速率常数，并用单纯形优化方法进行了反应路径计算。 最后，介绍了对单纯形法构型优化程序——SIMPLEX的改进及功能扩充。更多还原

【Abstract】 Four parts of the work are included in this thesis: The study on the reaction kinetics of OH radical with hexachlorobenzene (HCB); the reaction of Criegee radical; the calculation of the rate constant of the reaction of C2H2 and the supplement and the improvement for the program SIMPLEX. DFT and AM1 methods were used to study the reaction of OH radical with HCB, a poisonous chemical in gas phase, which is considered to be one of the decomposing ways of I-ICB in the atmosphere. The optimized structures of the reactants, the products and the transition states were found. A reasonable reaction path was determined through IRC calculations. The activation energy obtained is in good agreement with the experimental values. The intermediate Criegee radical is the source of some important pollutants in the atmosphere. It is difficult to study the reaction of Criegee radical experimentally since the Criegee radical is very unstable, so we study the reaction in theory on both thermodynamics and dynamics. A potential energy surface (PES) accurate enough can provide all the information needed for a chemical reaction, the curve from a valley (reactant) of the PES to another valley (product) of the PES along the minimum energy path (MEP) form the reaction path. The rate constant of the reaction can be calculated from the MEP using variational transition state theory (VTST). The rate constants of some reactions of C2H2 are calculated using VTST. Some supplement and improvement have been done to the structure optimization program SIMPLEX.更多还原