Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA.
J Chem Phys. 2013 Jun 21;138(23):234104. doi: 10.1063/1.4810007.
To provide a systematic and rigorous re-examination of the well-known Polanyi's rules, excitation functions of several A + BC(v = 0, 1) reactions are determined using the Chebyshev real wave packet method on accurate potential energy surfaces. Reactions with early (F + H2 and F + HCl), late (Cl + H2), and central (H∕D∕Mu + H2, where Mu is a short-lived light isotope of H) barriers are represented. Although Polanyi's rules are in general consistent with the quantum dynamical results, their predictions are strictly valid only in certain energy ranges divided by a cross-over point. In particular, vibrational excitation of the diatomic reactant typically enhances reactivity more effectively than translational excitation at high energies, while reverse is true at low energies. This feature persists irrespective of the barrier location. A sudden vector projection model is proposed as an alternative to Polanyi's rules. It is found to give similar, but more quantitative, predictions about mode selectivity in these reactions, and has the advantage to be extendible to reactions involving polyatomic molecules.
为了对著名的波兰尼规则进行系统而严格的重新检验，我们使用切比雪夫实波包方法在精确的势能面上确定了几个 A + BC(v = 0, 1)反应的激发函数。这些反应包括早期（F + H2 和 F + HCl）、晚期（Cl + H2）和中心（H∕D∕Mu + H2，其中 Mu 是 H 的短寿命轻同位素）势垒。虽然波兰尼规则通常与量子动力学结果一致，但它们的预测仅在由交叉点分隔的某些能量范围内严格有效。特别是在高能下，双原子反应物的振动激发比平移激发更有效地增强反应性，而在低能下则相反。这个特征与势垒位置无关。提出了一种突发向量投影模型作为波兰尼规则的替代方案。结果发现，它对这些反应中模式选择性的预测具有相似但更定量的效果，并且具有扩展到涉及多原子分子的反应的优势。
