Performance of Localized Coupled Cluster Methods in a Moderately Strong Correlation Regime: Hückel–Möbius Interconversions in Expanded Porphyrins
Performance of Localized Coupled Cluster Methods in a Moderately Strong Correlation Regime: Hückel–Möbius Interconversions in Expanded Porphyrins
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局部耦合聚类方法在中等强相关机制中的性能：扩展卟啉中的休克尔-莫比乌斯互变
DOI：
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发表时间：
2020
影响因子：
5.5
通讯作者：
Jan M. L. Martin
中科院分区：
文献类型：
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作者：
Nitai Sylvetsky;Ambar Banerjee;M. Alonso;Jan M. L. Martin
定域轨道耦合团簇理论是最近出现的一种大系统密度泛函理论的非经验替代方法。直觉上，人们可能会认为这种方法在高度非局部化的系统中表现不佳。在目前的工作中，我们将正则CCSD(T)近似和各种局域近似应用于一组灵活的扩展卟啉--在外部刺激下可以在Hück el、Figure-8和Möbius拓扑之间切换的大环。同时考虑了极小过渡态和异构化过渡态。我们发现Möbius(类)结构比其余的结构具有更强的静态相关性，这导致了DLPNO-CCSD(T)甚至DLPNO-CCSD(T1)方法的显著误差，除非采用TightPno截止。如果即使对于Möbius类系统(或其他被强静态关联所困扰的系统)，也需要相对于正则相对能量的亚千卡的摩尔-1精度，那么Nagy和Kallay的“紧”设置的LNO-CCSD(T)方法是合适的局域化方法。我们建议将目前的POLYPYR21数据集作为定域轨道方法的基准，或者更广泛地说，作为低水平方法处理具有强烈变化的静态关联程度的能量学的能力的基准。
Localized orbital coupled cluster theory has recently emerged as a nonempirical alternative to DFT for large systems. Intuitively, one might expect such methods to perform less well for highly delocalized systems. In the present work, we apply both canonical CCSD(T) approximations and a variety of localized approximations to a set of flexible expanded porphyrins—macrocycles that can switch between Hückel, figure-eight, and Möbius topologies under external stimuli. Both minima and isomerization transition states are considered. We find that Möbius(-like) structures have much stronger static correlation character than the remaining structures, and that this causes significant errors in DLPNO-CCSD(T) and even DLPNO-CCSD(T1) approaches, unless TightPNO cutoffs are employed. If sub-kcal mol–1 accuracy with respect to canonical relative energies is required even for Möbius-type systems (or other systems plagued by strong static correlation), then Nagy and Kallay’s LNO-CCSD(T) method with “tight” settings is the suitable localized approach. We propose the present POLYPYR21 data set as a benchmark for localized orbital methods or, more broadly, for the ability of lower-level methods to handle energetics with strongly varying degrees of static correlation.