Group of Bioprocess and Biomedical Engineering, Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland.
Crystallography Group, Department of Geosciences, University of Bremen, Klagenfurter Straße, 28359 Bremen, Germany.
J Chem Phys. 2018 Aug 14;149(6):064110. doi: 10.1063/1.5030493.
The adequate choice of the interaction model is essential to reproduce qualitatively and estimate quantitatively the experimentally observed characteristics of materials or phenomena in computer simulations. Here we present the results of a benchmarking of density-functional theory calculations of rigid and flexible metal-organic frameworks (MOFs). The stability of these systems depends on the dispersion interactions. We compare the performance of two functionals, Perdew-Burke-Ernzerhof (PBE) and PBE designed for solids, with and without the dispersion corrections (D2 and TS), in reproducing the high-accuracy low-temperature X-ray and neutron diffraction data for both groups of MOFs. We focus our analysis on the key structural parameters: the lattice parameters, bond lengths, and angles. We show that the dispersion long range correction is essential to stabilize the structures and, in some cases, to converge the system to a geometry that is in line with the experimentally observed structure, especially for breathing MIL-53 structures or zeolitic imidazolate frameworks. We find that for all structures and all analyzed parameters, the D2-corrected PBE functional performs the best, except for bonds involving the metal ions; however, even for these bonds the difference between the experimentally observed and calculated lengths is small. Therefore, we recommend the use of the PBE-D2 functional in further numerical analyses of rigid and flexible nanoporous MOFs.
适当选择相互作用模型对于在计算机模拟中定性地再现和定量地估计材料或现象的实验观测特性至关重要。在这里，我们对刚性和柔性金属有机骨架（MOF）的密度泛函理论计算进行了基准测试，以展示结果。这些系统的稳定性取决于色散相互作用。我们比较了两种泛函（PBE 和专为固体设计的 PBE）的性能，以及在没有（D2 和 TS）和具有色散校正时，它们在再现两组 MOF 的高精度低温 X 射线和中子衍射数据方面的表现。我们将分析重点放在关键结构参数上：晶格参数、键长和键角。我们表明，色散长程校正对于稳定结构是必不可少的，在某些情况下，对于收敛到与实验观测结构一致的几何形状是必不可少的，特别是对于呼吸 MIL-53 结构或沸石咪唑骨架。我们发现，对于所有结构和所有分析的参数，D2 校正的 PBE 泛函表现最佳，除了涉及金属离子的键之外；然而，即使对于这些键，实验观测到的和计算出的长度之间的差异也很小。因此，我们建议在进一步的刚性和柔性纳米多孔 MOF 的数值分析中使用 PBE-D2 泛函。
