Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
Departamento de Química Física, Facultad de Ciencias Químicas, Universidad de Salamanca, 37008 Salamanca, Spain.
J Chem Phys. 2019 Sep 7;151(9):094307. doi: 10.1063/1.5111844.
This paper presents two new adiabatic, global potential energy surfaces (PESs) for the two lowest A' and A″ electronic states of the O(P) + H system. For each of these states, ab initio electronic energies were calculated for more than 5000 geometries using internally contracted multireference configuration interaction methods. The calculated points were then fitted using the ansatz by Aguado et al. [Comput. Phys. Commun. 108, 259 (1998)] leading to very accurate analytical potentials well adapted to perform reaction dynamics studies. Overall, the topographies of both PESs are in good agreement with the benchmark potentials of Rogers et al. [J. Phys. Chem. A 104, 2308 (2000)], but those presented in this work reproduce better the height and degeneracy of the two states at the saddle point. Moreover, the long range potential in the entrance channel does not require any cutoff. These features make the new PESs particularly suitable for a comparison of the dynamics on each of them. The new set of PESs was then used to perform quantum mechanics and quasiclassical trajectory calculations to determine differential and integral cross sections, which are compared to the experimental measurements by Garton et al. [J. Chem. Phys. 118, 1585 (2003)].
本文提出了 O(P) + H 体系两个最低 A' 和 A″ 电子态的两个新的绝热、全局势能面 (PES)。对于这两个态，我们使用内收缩多参考组态相互作用方法计算了超过 5000 个构型的从头算电子能。然后，使用 Aguado 等人的 ansatz [Comput. Phys. Commun. 108, 259 (1998)] 对计算点进行拟合，得到了非常精确的解析势，非常适合进行反应动力学研究。总的来说，这两个 PES 的地形与 Rogers 等人的基准势能 [J. Phys. Chem. A 104, 2308 (2000)] 非常吻合，但本工作提出的势能更好地再现了鞍点处两个态的高度和简并度。此外，入口通道中的长程势能不需要任何截止。这些特点使得新的 PES 特别适合对它们各自的动力学进行比较。新的 PES 集随后用于进行量子力学和准经典轨迹计算，以确定微分和积分截面，并与 Garton 等人的实验测量 [J. Chem. Phys. 118, 1585 (2003)] 进行比较。
