Jawahery Sudi, Rampal Nakul, Moosavi Seyed Mohamad, Witman Matthew, Smit Berend
Department of Chemical and Biomolecular Engineering , University of California , Berkeley , California 94720 , United States.
Laboratory of Molecular Simulation (LSMO), Institut des Sciences et Ingénierie Chimiques, Valais , École Polytechnique Fédérale de Lausanne (EPFL) , Rue de l'Industrie 17 , CH-1951 Sion , Switzerland.
J Chem Theory Comput. 2019 Jun 11;15(6):3666-3677. doi: 10.1021/acs.jctc.9b00135. Epub 2019 May 22.
We present force fields developed from periodic density functional theory (DFT) calculations that can be used in classical molecular simulations to model M-MOF-74 (M = Co, Fe, Mg, Mn, Ni, Zn) and its extended linker analogs. Our force fields are based on cationic dummy models (CDMs). These dummy models simplify the methodology required to tune the parameters and improve the accuracy of the force fields. We used our force fields to compare mechanical properties across the M-MOF-74 series and determine that increasing the size of the linker decreases the framework rigidity. In addition, we applied our force fields to an extended linker analog of Mg-MOF-74 and characterized the free energy of a previously reported deformation pattern in which the one-dimensional hexagonal channels of the framework become irregular. The free energy profiles confirm that the deformation is adsorbate induced and impossible to access solely by a pressure stimulus. On the basis of our results, we conclude that the force fields presented here and others that may be developed using our methodology are transferable across metal-organic framework series that share a metal center topology. Finally, we believe that these force fields have the potential to be adapted for the study of complex problems in MOF chemistry, including defects and crystal growth, that have thus far been beyond the scope of classical molecular simulations.
我们展示了通过周期性密度泛函理论（DFT）计算开发的力场，这些力场可用于经典分子模拟，以模拟M-MOF-74（M = Co、Fe、Mg、Mn、Ni、Zn）及其扩展的连接体类似物。我们的力场基于阳离子虚拟模型（CDM）。这些虚拟模型简化了调整参数所需的方法，并提高了力场的准确性。我们使用我们的力场比较了M-MOF-74系列的力学性能，并确定增加连接体的尺寸会降低骨架刚性。此外，我们将我们的力场应用于Mg-MOF-74的扩展连接体类似物，并表征了先前报道的一种变形模式的自由能，在该变形模式中，骨架的一维六边形通道变得不规则。自由能分布证实了这种变形是由吸附质引起的，仅通过压力刺激是无法实现的。基于我们的结果，我们得出结论，这里展示的力场以及其他可能使用我们的方法开发的力场，可在具有相同金属中心拓扑结构的金属有机框架系列之间转移。最后，我们相信这些力场有潜力适用于研究MOF化学中的复杂问题，包括缺陷和晶体生长，而这些问题迄今为止超出了经典分子模拟的范围。
