Jíra Tomáš, Janoš Jiří, Slavíček Petr
Department of Physical Chemistry, University of Chemistry and Technology, Technická 5, Prague 6 16628, Czech Republic.
J Chem Theory Comput. 2024 Dec 24;20(24):10972-10985. doi: 10.1021/acs.jctc.4c01008. Epub 2024 Dec 12.
The techniques of computational photodynamics are increasingly employed to unravel reaction mechanisms and interpret experiments. However, misinterpretations in nonadiabatic dynamics caused by inaccurate underlying potentials are often difficult to foresee. This work focuses on revealing the systematic errors in the nonadiabatic simulations due to the underlying potentials and suggests a thrifty approach to evaluate the sensitivity of the simulations to the potential. This issue is exemplified in the photochemistry of -stilbene, where similar experimental outcomes have been differently interpreted based on the electronic structure methods supporting nonadiabatic dynamics. We examine the predictions of -stilbene photochemistry using trajectory surface hopping methods coupled with various electronic structure methods (OM3-MRCISD, SA2-CASSCF, XMS-SA2-CASPT2, and XMS-SA3-CASPT2) and assess their ability to interpret experimental observations. While the excited-state lifetimes and calculated photoelectron spectra show consistency with experiments, the reaction quantum yields vary significantly: either completely suppressing cyclization or isomerization. Intriguingly, analyzing stationary points on the potential energy surface does not hint at any major discrepancy, making the electronic structure methods seemingly reliable when treated separately. We show that performing an ensemble of simulations with different potentials provides an estimate of the electronic structure sensitivity. However, this ensemble approach is costly. Thus, we propose running nonadiabatic simulations with an external bias at a resource-efficient underlying potential (semiempirical or machine-learned) for the sensitivity analysis. We demonstrate this approach using a semiempirical OM3-MRCISD method with a harmonic bias toward cyclization.
计算光动力学技术越来越多地用于揭示反应机理和解释实验结果。然而，由不准确的基础势能引起的非绝热动力学中的错误解释往往难以预见。这项工作的重点是揭示由于基础势能导致的非绝热模拟中的系统误差，并提出一种经济的方法来评估模拟对势能的敏感性。在反式芪的光化学中就体现了这个问题，基于支持非绝热动力学的电子结构方法，类似的实验结果得到了不同的解释。我们使用轨迹表面跳跃方法结合各种电子结构方法（OM3-MRCISD、SA2-CASSCF、XMS-SA2-CASPT2和XMS-SA3-CASPT2）来检验反式芪光化学的预测，并评估它们解释实验观测结果的能力。虽然激发态寿命和计算得到的光电子能谱与实验结果一致，但反应量子产率却有很大差异：要么完全抑制环化，要么抑制异构化。有趣的是，分析势能面上的驻点并没有暗示任何重大差异，这使得单独处理时电子结构方法看似可靠。我们表明，用不同的势能进行一系列模拟可以估计电子结构的敏感性。然而，这种系列方法成本很高。因此，我们建议在资源高效的基础势能（半经验或机器学习）下运行带有外部偏差的非绝热模拟进行敏感性分析。我们使用对环化有谐波偏差的半经验OM3-MRCISD方法证明了这种方法。
