Zhao Huali, Wang Wenji, Zhao Yi
College of Science, Northwest A&F University , Yangling, 712100 Shaanxi Province, P. R. China.
State Key Laboratory for Physical Chemistry of Solid Surfaces and Fujian Provincial Key Lab of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, P. R. China.
J Phys Chem A. 2016 Oct 6;120(39):7589-7597. doi: 10.1021/acs.jpca.6b07029. Epub 2016 Sep 26.
The rate constants and kinetic isotope effects for the O(P) + CH reaction have been investigated with the quantum instanton method in full dimensionality. The calculated rate constants are in good agreement with the experimental values above 400 K, below which the measured values are scattered. Compared to other theoretical approaches, the quantum instanton method predicts the largest quantum tunneling effect, so it gives the largest rate constants at low temperatures. The calculated kinetic isotope effects are always much larger than 1 and increase with decreasing temperature, due to the zero-point energy and quantum tunneling. Our calculations on different potential energy surfaces demonstrate that the potential energy barrier shape dominates the magnitude of quantum tunneling and has a great effect on the kinetic isotope effect.
采用全维量子瞬子方法研究了O(P) + CH反应的速率常数和动力学同位素效应。计算得到的速率常数与400 K以上的实验值吻合良好，低于该温度时测量值分散。与其他理论方法相比，量子瞬子方法预测的量子隧穿效应最大，因此在低温下给出的速率常数最大。由于零点能和量子隧穿，计算得到的动力学同位素效应总是远大于1，并随温度降低而增加。我们在不同势能面上的计算表明，势能垒形状主导量子隧穿的大小，并对动力学同位素效应有很大影响。
