Box Connor L, Zhang Yaolong, Yin Rongrong, Jiang Bin, Maurer Reinhard J
Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom.
Hefei National Laboratory for Physical Science at the Microscale, Department of Chemical Physics, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, Anhui 230026, China.
JACS Au. 2020 Dec 22;1(2):164-173. doi: 10.1021/jacsau.0c00066. eCollection 2021 Feb 22.
Nonadiabatic effects that arise from the concerted motion of electrons and atoms at comparable energy and time scales are omnipresent in thermal and light-driven chemistry at metal surfaces. Excited (hot) electrons can measurably affect molecule-metal reactions by contributing to state-dependent reaction probabilities. Vibrational state-to-state scattering of NO on Au(111) has been one of the most studied examples in this regard, providing a testing ground for developing various nonadiabatic theories. This system is often cited as the prime example for the failure of electronic friction theory, a very efficient model accounting for dissipative forces on metal-adsorbed molecules due to the creation of hot electrons in the metal. However, the exact failings compared to experiment and their origin from theory are not established for any system because dynamic properties are affected by many compounding simulation errors of which the quality of nonadiabatic treatment is just one. We use a high-dimensional machine learning representation of electronic structure theory to minimize errors that arise from quantum chemistry. This allows us to perform a comprehensive quantitative analysis of the performance of nonadiabatic molecular dynamics in describing vibrational state-to-state scattering of NO on Au(111) and compare directly to adiabatic results. We find that electronic friction theory accurately predicts elastic and single-quantum energy loss but underestimates multiquantum energy loss and overestimates molecular trapping at high vibrational excitation. Our analysis reveals that multiquantum energy loss can potentially be remedied within friction theory whereas the overestimation of trapping constitutes a genuine breakdown of electronic friction theory. Addressing this overestimation for dynamic processes in catalysis and surface chemistry will likely require more sophisticated theories.
在金属表面的热化学和光驱动化学中，电子和原子在相当的能量和时间尺度上协同运动所产生的非绝热效应无处不在。激发态（热）电子可通过影响与状态相关的反应概率，对分子 - 金属反应产生显著影响。NO在Au(111)上的振动态到振动态散射一直是这方面研究最多的例子之一，为发展各种非绝热理论提供了一个试验场。该系统常被引为电子摩擦理论失效的典型例子，电子摩擦理论是一个非常有效的模型，用于解释由于金属中产生热电子而作用于金属吸附分子上的耗散力。然而，对于任何系统而言，与实验相比的确切不足之处及其理论根源尚未明确，因为动态性质受到许多复合模拟误差的影响，其中非绝热处理的质量只是其中之一。我们使用电子结构理论的高维机器学习表示来最小化量子化学产生的误差。这使我们能够对非绝热分子动力学在描述NO在Au(111)上的振动态到振动态散射的性能进行全面定量分析，并直接与绝热结果进行比较。我们发现电子摩擦理论准确地预测了弹性和单量子能量损失，但低估了多量子能量损失，并高估了高振动激发下的分子捕获。我们的分析表明，多量子能量损失在摩擦理论框架内有可能得到修正，而捕获的高估则构成了电子摩擦理论的真正失效。解决催化和表面化学中动态过程的这种高估问题可能需要更复杂的理论。
