Zhai Huanchen, Alexandrova Anastassia N
Department of Chemistry and Biochemistry , University of California, Los Angeles , Los Angeles , California 90095 , United States.
California NanoSystems Institute , Los Angeles , California 90095 , United States.
J Phys Chem Lett. 2018 Apr 5;9(7):1696-1702. doi: 10.1021/acs.jpclett.8b00379. Epub 2018 Mar 21.
Subnano surface-supported catalytic clusters can be generally characterized by many low-energy isomers accessible at elevated temperatures of catalysis. The most stable isomer may not be the most catalytically active. Additionally, isomers may interconvert across barriers, i.e., exhibit fluxionality, during catalysis. To study the big picture of the cluster fluxional behavior, we model such a process as isomerization graph using bipartite matching algorithm, harmonic transition state theory, and paralleled nudged elastic band method. All the minimal energy paths form a minimum spanning tree (MST) of the original graph. Detailed inspection shows that, at temperatures typical for catalysis, the cluster geometry changes frequently within several regions in the MST, while transition across regions is less likely. As a further confirmation, the structural similarity analysis was additionally performed based on molecular dynamics trajectories. This local fluxionality picture provides a new perspective on understanding finite-temperate catalytic processes.
亚纳米表面支撑的催化簇通常可以通过许多在催化高温下可及的低能异构体来表征。最稳定的异构体可能不是催化活性最高的。此外，异构体在催化过程中可能会跨越势垒相互转化，即表现出分子流动性。为了研究簇分子流动性行为的全貌，我们使用二分匹配算法、谐振过渡态理论和平行推挤弹性带方法将这样一个过程建模为异构化图。所有最小能量路径形成原始图的最小生成树（MST）。详细检查表明，在催化的典型温度下，簇的几何结构在MST的几个区域内频繁变化，而跨区域的转变则不太可能。作为进一步的证实，还基于分子动力学轨迹进行了结构相似性分析。这种局部分子流动性图景为理解有限温度催化过程提供了一个新的视角。
