A time-dependent quantum dynamical study of the H + HBr reaction.
A time-dependent quantum dynamical study of the H + HBr reaction.
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DOI：
10.1021/jp073811z
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发表时间：
2007-09
期刊：
影响因子：
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通讯作者：
Bina Fu;Dong H. Zhang
中科院分区：
文献类型：
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作者：
Bina Fu;Dong H. Zhang
在Kurosaki-Takayanagi势能面上，用含时波包计算研究了标题反应中的交换和提取过程（Kurosaki，Y.; Takayanagi，T. J. Chem.Phys.2003，119，7838）。计算了反应物HBr初始处于基态、第一旋转激发态和第一振动激发态的交换反应和提取反应的总反应几率和积分截面。在低碰撞能下，由于势垒高度低，只发生抽离反应。一旦碰撞能量超过交换反应的势垒高度，交换过程迅速成为主导过程，可能是由于其较大的接受锥。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处的理论截面为1.06 A（2），其比3 +/-1 A（2）的实验结果小2-3倍。另一方面，在220 - 550 K的温度范围内，理论速率常数比实验结果大约2倍。在200 K时，量子速率常数比TST结果大2倍。然而，本量子速率常数和TST的结果之间的协议，改善随着温度的升高。
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.