Chen Bozhu, Xu Xin
Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Ministry of Education Key Laboratory of Computational Physical Sciences, Department of Chemistry, Fudan University, Shanghai, 200433, China.
J Chem Theory Comput. 2020 Jul 14;16(7):4271-4285. doi: 10.1021/acs.jctc.0c00232. Epub 2020 Jun 10.
In this work, we propose the XO-PBC method, which combines the eXtended ONIOM method (XO) with the periodic boundary condition (PBC) for the description of molecular crystals. XO-PBC tries to embed a finite cluster cut out from the solid into the periodic environment, making it feasible to employ advanced molecular quantum chemistry methods, which are usually prohibitively expensive for direct PBC calculations. In particular, XO-PBC utilizes the results from force calculations to design the scheme to fragment the molecule when crystals are made of large molecules and to select cluster model systems automatically consisting of dimer up to tetramer interactions for embedding. By applying an appropriate theory to each model, a satisfactory accuracy for the system under study is ensured, while a high efficiency is achieved with massively parallel computing by distributing model systems onto different processors. A comparison of the XO-PBC calculations with the conventional direct PBC calculations at the B3LYP level demonstrates its accuracy at substantially low cost for the description of molecular crystals. The usefulness of the XO-PBC method is further exemplified, showing that XO-PBC is able to predict the lattice energies of various types of molecular crystals within chemical accuracy (<4 kJ/mol) when the doubly hybrid density functional XYG3 is used as the target high level and the periodic PBE as the basic low level. The XO-PBC method provides a general protocol that brings the great predictive power of advanced electronic structure methods from molecular systems to the extended solids.
在这项工作中，我们提出了XO-PBC方法，该方法将扩展的ONIOM方法（XO）与周期性边界条件（PBC）相结合用于描述分子晶体。XO-PBC试图将从固体中截取的有限簇嵌入到周期性环境中，从而使得采用先进的分子量子化学方法成为可能，而这些方法对于直接的PBC计算通常成本过高。特别地，当晶体由大分子构成时，XO-PBC利用力计算的结果来设计分子碎片化方案，并自动选择由二聚体到四聚体相互作用组成的簇模型系统用于嵌入。通过对每个模型应用适当的理论，在确保所研究系统具有令人满意精度的同时，通过将模型系统分布到不同处理器上进行大规模并行计算，实现了高效率。在B3LYP水平下，将XO-PBC计算结果与传统的直接PBC计算结果进行比较，证明了其在以相当低的成本描述分子晶体方面的准确性。XO-PBC方法的实用性进一步得到例证，结果表明，当使用双杂化密度泛函XYG3作为目标高水平理论且周期性PBE作为基本低水平理论时，XO-PBC能够在化学精度（<4 kJ/mol）内预测各种类型分子晶体的晶格能。XO-PBC方法提供了一个通用的方案，将先进电子结构方法从分子体系的强大预测能力扩展到了扩展固体体系。
