Department of Chemistry, Indian Institute of Technology, Guwahati, 781039, India.
Phys Chem Chem Phys. 2012 Oct 5;14(37):13067-75. doi: 10.1039/c2cp41825h.
We present a detailed theoretical investigation of the dynamics corresponding to the strongly endothermic Br + H(2) (v = 0-1, j = 0) → H + HBr reaction in the 0.85 to 1.9 eV total energy range. State-averaged and state-to-state results obtained through time-independent wave packet (TIWP) and time-independent quantum mechanical (TIQM) calculations and quasiclassical trajectories (QCT) are compared and analyzed. The agreement in the results obtained with both quantum mechanical results is very good overall. However, although QCT calculations reproduce the general features, their agreement with the QM results is sometimes only qualitative. The analysis of the mechanism based on state-averaged results turns out to be deceptive and conveys an oversimplified picture of the reaction consistent with a direct-rebound mechanism. Consideration of state-to-state processes, in contrast, unveils the existence of multiple mechanisms that give rise to a succession of maxima in the differential cross section (DCS). Such mechanisms correlate with different sets of partial waves and display similar collision times when analyzed through the time-dependent DCS.
我们对总能量范围在 0.85 到 1.9 eV 的强吸热 Br + H(2) (v = 0-1, j = 0) → H + HBr 反应的动力学进行了详细的理论研究。通过时间无关波包 (TIWP) 和时间无关量子力学 (TIQM) 计算以及准经典轨迹 (QCT) 获得的态平均和态到态结果进行了比较和分析。总的来说，通过两种量子力学方法获得的结果非常吻合。然而，尽管 QCT 计算可以再现一般特征，但它们与 QM 结果的一致性有时仅具有定性意义。基于态平均结果的机制分析结果具有欺骗性，它传达了一种与直接反弹机制一致的过于简化的反应图像。相比之下，考虑到态到态过程，揭示了存在多种机制，这些机制导致微分截面 (DCS) 中出现一系列最大值。这些机制与不同的部分波相关联，并且在通过时间相关的 DCS 进行分析时显示出相似的碰撞时间。
