Wu Jia-Yan, Liu Jing-Yao, Li Ze-Sheng, Huang Xu-Ri, Sun Chia-Chung
Institute of Theoretical Chemistry, State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun 130023, People's Republic of China.
J Comput Chem. 2003 Apr 15;24(5):593-600. doi: 10.1002/jcc.10219.
The dual-level direct dynamics approach is employed to study the dynamics of the CH(3)OCH(3) + H (R1) and CH(3)OCH(3) + CH(3) (R2) reactions. Low-level calculations of the potential energy surface are carried out at the MP2/6-311+G(d,p) level of theory. High-level energetic information is obtained at the QCISD(T) level of theory with the 6-311+G(3df,3pd) basis set. The dynamics calculations are performed using variational transition state theory (VTST) with the interpolated single-point energies (ISPE) method, and small-curvature tunneling (SCT) is included. It is shown that the reaction of CH(3)OCH(3) with H (R1) may proceed much easier and with a lower barrier height than the reaction with CH(3) radical (R2). The calculated rate constants and activation energies are in good agreement with the experimental values. The calculated rate constants are fitted to k(R1) = 1.16 x 10(-19) T(3) exp(-1922/T) and k(R2) = 1.66 x 10(-28) T(5) exp(-3086/T) cm(3) mol(-1) s(-1) over a temperature range 207-2100 K. Furthermore, a small variational effect and large tunneling effect in the lower temperature range are found for the two reactions.
采用双水平直接动力学方法研究CH(3)OCH(3)+H（反应R1）和CH(3)OCH(3)+CH(3)（反应R2）的动力学。在MP2/6 - 311+G(d,p)理论水平上进行势能面的低水平计算。在QCISD(T)理论水平上使用6 - 311+G(3df,3pd)基组获得高水平的能量信息。动力学计算采用变分过渡态理论（VTST）和内插单点能量（ISPE）方法，并包含小曲率隧道效应（SCT）。结果表明，CH(3)OCH(3)与H的反应（R1）可能比与CH(3)自由基的反应（R2）更容易进行，且势垒高度更低。计算得到的速率常数和活化能与实验值吻合良好。在207 - 2100 K的温度范围内，计算得到的速率常数拟合为k(R1)=1.16×10(-19)T(3)exp(-1922/T)和k(R2)=1.66×10(-28)T(5)exp(-3086/T) cm(3) mol(-1) s(-1)。此外，发现这两个反应在较低温度范围内存在小的变分效应和大的隧道效应。
