The Fritz Haber Center for Molecular Dynamics, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Theoretical Physical Chemistry, UR MolSys B6c, University of Liège, B4000 Liège, Belgium.
J Chem Phys. 2023 Apr 28;158(16). doi: 10.1063/5.0148798.
Multi-state electronic dynamics at higher excitation energies is needed for the understanding of a variety of energy rich situations, including chemistry under extreme conditions, vacuum ultraviolet (VUV) induced astrochemistry, and attochemistry. It calls for an understanding of three stages, energy acquisition, dynamical propagation, and disposal. It is typically not possible to identify a basis of uncoupled quantum states that is sufficient for the three stages. The handicap is the large number of coupled quantum states that is needed to describe the system. Progress in quantum chemistry provides the necessary background to the energetics and the coupling. Progress in quantum dynamics takes this as input for the propagation in time. Right now, it seems that we have come of age with potential detailed applications. We here report a demonstration to a coupled electron-nuclear quantum dynamics through a maze of 47 electronic states and with attention to the order in perturbation theory that is indicated using propensity rules for couplings. Close agreement with experimental results for the VUV photodissociation of 14N2 and its isotopomer 14N15N is achieved. We pay special attention to the coupling between two dissociative continua and an optically accessible bound domain. The computations reproduce and interpret the non-monotonic branching between the two exit channels producing N(2D) and N(2P) atoms as a function of excitation energy and its variation with the mass.
需要了解更高激发能下的多态电子动力学，以理解各种能量丰富的情况，包括极端条件下的化学、真空紫外 (VUV) 诱导的天体化学和原子化学。它需要了解三个阶段：能量获取、动力学传播和处理。通常不可能确定一个足以满足三个阶段的非耦合量子态的基础。障碍是需要描述系统所需的大量耦合量子态。量子化学的进展为能学和耦合提供了必要的背景。量子动力学的进展将其作为时间传播的输入。现在，似乎我们已经到了可以进行详细应用的时代。我们在这里报告了通过 47 个电子态的迷宫进行的电子-核量子动力学的耦合演示，并注意到使用耦合倾向规则指示的微扰理论中的顺序。与 14N2 和其同位素 14N15N 的 VUV 光解的实验结果非常吻合。我们特别关注两个离解连续区和一个光可及的束缚区之间的耦合。计算结果再现并解释了作为激发能函数的两个出口通道之间的非单调分支，以及质量变化对其的影响，产生 N(2D) 和 N(2P) 原子。
