利用密度泛函理论直接动力学方法研究了反应CH3OCF2CF2OCH3+Cl的微观机理和动力学性质.在BB1K/6-31+G(d,p)水平上获得了反应的势能面信息,计算中考虑了反应物CH3OCF2CF2OCH3两个稳定构象(SC1和SC2)的氢提取通道和取代反应通道.利用改进的正则变分过渡态理论结合小曲率隧道效应(ICVT/SCT)计算了各氢提取通道的速率常数,进而根据Boltzmann配分函数得到总包反应速率常数(KT)以及每个构象对总反应的贡献.结果表明296 K温度下计算的kT(ICVT/SCT)值与已有实验值符合得很好.由于缺乏其他温度速率常数的实验数据,我们预测了该反应在200-2000 K温度区间内反应速率常数的三参数表达式:kT=0.40×10-44T1.05exp(-206.16/T).%A direct density functional theory dynamics method was used to determine the mechanism and kinetics of the CH3OCF2CF2OCH3+Cl reaction.Potential energy surface information was obtained at the BB1K/6-31+G(d,p) level.The hydrogen abstraction channels and displacement processes of the two stable conformers (SC1 and SC2) of CH3OCF2CF2OCH3 were taken into consideration.Theoretical rate constants of the individual H-abstraction channels (one from SC1 and two from SC2) were calculated by improved canonical variational transition state theory (ICVT) with a small-curvature tunneling (SCT) correction.The overall rate constant (kT) was obtained by considering the weight factor of each conformer from the Boltzmann distribution function and the contribution of the two conformers to the whole reaction was discussed.The calculated kT(ICVT/SCT) at 296 K agrees well with the experimental value.Since experimental data were lacking for other temperatures, a three-parameter rate constant temperature expression for the total reaction within 200-2000 K was fitted to: kT=0.40×10-14T1.05exp(-206.16/T).
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