【作者】 王玲；

【导师】 王秀岩； 杨学明；

【作者基本信息】 中国科学院研究生院（大连化学物理研究所） ， 物理化学， 2006， 博士

【摘要】 本论文主要分为两部分,一部分是应用ab initio/RRKM理论对碰撞解离反应进行了详细研究。另一部分是利用插值的方法构建四原子光解反应的全维势能面。应用ab initio/RRKM理论研究的第一个反应体系是O（¹D） + NH₃碰撞反应,该反应主要通过插入机制进行,也就是生成了长寿命的活化中间体NH₂OH*。这个高能量的中间体通过一些关键的构象解离生成各种产物。计算得到的NH₂OH*解离产物的分支比与实验结果符合得很好。该反应还可以通过抽取机制发生在第一激发态上,部分解释了实验中观察到的OH产物的向前散射。F + CH₃双自由基碰撞可以无能垒地形成CH₃F中间体,应用RRKM理论计算了在不同的碰撞能和温度下CH₃F解离通道的速率常数和分支比。理论计算预测H + CH₂F是主要反应产物（除低温情况）,其次是H₂ + CHF。H抽取机制生成了HF + CH₂,该反应能垒很低,1.4kcal/mol,在高碰撞能和温度下对产物的贡献变大。在化学动力学研究中,精确的势能面是动力学计算的基础。不管是化学反应的宏观热速率常数,还是它的微观速率常数,都可以根据势能面来解释。基于势能面的重要性,在QCISD/aug-cc-pVTZ和CCSD（T）/aug-cc-pVQZ水平下构建了COHF光解反应的全维从头算势能面。该势能面是在相关的构象空间对从头算点的能量,一阶导数和二阶导数进行插值得到的。更多还原

【Abstract】 This dissertation is composed of two parts. The first part is the detailed studies of unimolecular dissociation reactions by ab initio/RRKM theory ; the second part is the construction of six-dimensional PES for four-atom photodissociation reaction by interpolated method.The first reaction system studied by ab initio/RRKM is O（¹D） + NH₃ collision reaction, which is shown to occur mainly through the insertion mechanism involving the long-lived chemically activated NH₂OH* intermediate. This energized intermediate quickly dissociates to various products via some critical configurations. The calculated branching ratios of various decomposition products of NH2OH* are in good agreement with recently reported experimental values. This reaction can also proceed through the addition/abstraction mechanism on the first excited-state PES, which partially accounts for the forward scattering of the OH products observed in experiment.The CH₃F intermediate can be formed without a barrier by F + CH₃ collision , then dissociate via four product channels, including F + CH₃, HF + CH₂, H₂ + CHF, and H + CH₂F. RRKM theory is applied to compute rate constants and branching ratios of the four product channels at various collision energies and temperatures. H + CH₂F are predicted to be the major reaction products （except at low temperatures） followed by H₂ + CHF. The H abstraction mechanism leading to HF + CH₂ over a low barrier, 1.4kcal/mol, is also important at high collision更多还原