三氟乙烷与氟原子氢提取反应的动力学研究

Dynamics of hydrogen abstraction reaction between trifluoroethane and fluorine atom

采用双水平直接动力学方法研究了氢提取反应CH3CF3＋F—CH2CF3＋HF的反应机理．首先用MPW1K／63u＋G（d，p）方法优化了驻点的几何构型，并在相同水平上进行了频率分析，利用内禀反应坐标理论获得了最小的反应能量途径；随后，为了得到更准确的能量信息，采用MCG3MPWPW91／／MPW1K方法进行了单点能量校正；最后，根据变分过渡态理论计算了该反应在200～2000K温度范围内的速率常数．结果表明，理论计算值与已有的实验值吻合．

The mechanisms of the hydrogen-abstraction reaction between 1,1,1-trifluoroethane （CH3CF3） and fluorine atom was studied by dual level direct dynamics method. Firstly, the geometries and frequencies of the stationary points were calculated at the MPWlK/6 311＋G （d,p） level, and the minimum energy path for the reaction was obtained by intrinsic reaction coordinate theory. Secondly, for acquiring accurate reaction enthalpy and potential barrier, the single point energies were calculated and corrected at the MCG3 MPWPW91//MPW1K level. Finally, the rate constant was calculated by using the variational transition state theory over a wide temperature range of 200--2 000 K. It has been found that the theoretical results agree well with currently available experimental ones.