Fu Bina, Zhang Dong H
State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, People's Republic of China 116023.
J Phys Chem A. 2007 Sep 27;111(38):9516-21. doi: 10.1021/jp073811z. Epub 2007 Aug 14.
Time-dependent wave packet calculations were carried out to study the exchange and abstraction processes in the title reaction on the Kurosaki-Takayanagi potential energy surface (Kurosaki, Y.; Takayanagi, T. J. Chem. Phys. 2003, 119, 7838). Total reaction probabilities and integral cross sections were calculated for the reactant HBr initially in the ground state, first rotationally excited state, and first vibrationally excited state for both the exchange and abstraction reactions. At low collision energy, only the abstraction reaction occurs because of its low barrier height. Once the collision energy exceeds the barrier height of the exchange reaction, the exchange process quickly becomes the dominant process presumably due to its larger acceptance cone. It is found that initial vibrational excitation of HBr enhances both processes, while initial rotational excitation of HBr from j(0) = 0 to 1 has essentially no effect on both processes. For the abstraction reaction, the theoretical cross section at E(c) = 1.6 eV is 1.06 A(2), which is smaller than the experimental result of 3 +/- 1 A(2) by a factor of 2-3. On the other hand, the theoretical rate constant is larger than the experimental results by about a factor of 2 in the temperature region between 220 and 550 K. It is also found that the present quantum rate constant is larger than the TST result by a factor of 2 at 200 K. However, the agreement between the present quantum rate constant and the TST result improves as the temperature increases.
进行了含时波包计算，以研究在黑崎 - 高柳势能面（黑崎，Y.；高柳，T. J. 化学物理杂志，2003年，119卷，7838页）上标题反应中的交换和提取过程。针对初始处于基态、第一转动激发态和第一振动激发态的反应物HBr，计算了交换和提取反应的总反应概率和积分截面。在低碰撞能量下，由于提取反应的势垒高度较低，只有提取反应发生。一旦碰撞能量超过交换反应的势垒高度，交换过程可能由于其更大的接受锥而迅速成为主导过程。研究发现，HBr的初始振动激发增强了这两个过程，而HBr从j(0) = 0到1的初始转动激发对这两个过程基本没有影响。对于提取反应，在E(c) = 1.6 eV时的理论截面为1.06 Ų，比3 ± 1 Ų的实验结果小2 - 3倍。另一方面，在220至550 K的温度范围内，理论速率常数比实验结果大约大2倍。还发现，在200 K时，当前的量子速率常数比TST结果大2倍。然而，随着温度升高，表示当前量子速率常数与TST结果之间的一致性提高。
