Center of Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, Box 1033 Blindern, N-0315, Oslo, Norway.
Phys Chem Chem Phys. 2011 Jun 7;13(21):10191-203. doi: 10.1039/c0cp02944k. Epub 2011 Apr 19.
Formation energies, chemical bonding, electronic structure, and optical properties of metal-organic frameworks of alkaline earth metals, A-IRMOF-1 (where A = Be, Mg, Ca, Sr, or Ba), have been systemically investigated with DFT methods. The unit cell volumes and atomic positions were fully optimized with the Perdew-Burke-Ernzerhof functional. By fitting the E-V data into the Murnaghan, Birch and Universal equation of states (UEOS), the bulk modulus and its pressure derivative were estimated and provided almost identical results. The data indicate that the A-IRMOF-1 series are soft materials. The estimated bandgap values are all ca. 3.5 eV, indicating a nonmetallic behavior which is essentially metal independent within this A-IRMOF-1 series. The calculated formation energies for the A-IRMOF-1 series are -61.69 (Be), -62.53 (Mg), -66.56 (Ca), -65.34 (Sr), and -64.12 (Ba) kJ mol(-1) and are substantially more negative than that of Zn-based IRMOF-1 (MOF-5) at -46.02 kJ mol(-1). From the thermodynamic point of view, the A-IRMOF-1 compounds are therefore even more stable than the well-known MOF-5. The linear optical properties of the A-IRMOF-1 series were systematically investigated. The detailed analysis of chemical bonding in the A-IRMOF-1 series reveals the nature of the A-O, O-C, H-C, and C-C bonds, i.e., A-O is a mainly ionic interaction with a metal dependent degree of covalency. The O-C, H-C, and C-C bonding interactions are as anticipated mainly covalent in character. Furthermore it is found that the geometry and electronic structures of the presently considered MOFs are not very sensitive to the k-point mesh involved in the calculations. Importantly, this suggests that sampling with Γ-point only will give reliable structural properties for MOFs. Thus, computational simulations should be readily extended to even more complicated MOF systems.
采用 DFT 方法系统研究了碱土金属金属有机骨架 A-IRMOF-1（其中 A=Be、Mg、Ca、Sr 或 Ba）的形成能、化学成键、电子结构和光学性质。采用 Perdew-Burke-Ernzerhof 泛函对单元晶胞体积和原子位置进行了全优化。通过将 E-V 数据拟合到 Murnaghan、Birch 和通用状态方程（UEOS）中，估算了体弹模量及其压力导数，并提供了几乎相同的结果。数据表明，A-IRMOF-1 系列是软物质。估算的带隙值均约为 3.5 eV，表明在该 A-IRMOF-1 系列中具有本质上与金属无关的非金属行为。A-IRMOF-1 系列的计算形成能为-61.69（Be）、-62.53（Mg）、-66.56（Ca）、-65.34（Sr）和-64.12（Ba）kJ/mol，比基于 Zn 的 IRMOF-1（MOF-5）的-46.02 kJ/mol 负得多。从热力学角度来看，A-IRMOF-1 化合物因此比著名的 MOF-5 更稳定。系统研究了 A-IRMOF-1 系列的线性光学性质。对 A-IRMOF-1 系列中化学键的详细分析揭示了 A-O、O-C、H-C 和 C-C 键的本质，即 A-O 主要是离子相互作用，具有金属依赖性程度的共价性。O-C、H-C 和 C-C 键合相互作用预期主要具有共价性质。此外，还发现目前考虑的 MOFs 的几何和电子结构对计算中涉及的 k 点网格不非常敏感。重要的是，这表明仅使用 Γ 点采样将为 MOFs 提供可靠的结构性质。因此，计算模拟应该很容易扩展到更复杂的 MOF 系统。
Zotero 插件