论文标题
分子晶体的多聚体嵌入方法，直至谐波振动特性
A Multimer Embedding Approach for Molecular Crystals up to Harmonic Vibrational Properties
论文作者
论文摘要
分子晶体的准确计算对于药物设计和晶体工程至关重要。但是，对于相关系统，使用混合功能的周期性高度密度功能计算通常非常昂贵。这些昂贵的周期性计算可以通过嵌入方法的使用来规避，例如，嵌入方法仅在较低成本水平上进行周期性计算，然后单体能量和二聚体相互作用被高级方法所取代。本文中，我们扩展了这种多聚体嵌入方法，以实现三聚体相互作用的能量校正以及将谐波振动特性的计算到二聚体水平。我们通过使用通用梯度近似（GGA）功能（PBE+MBD）将多聚体嵌入较低的计算中，通过近似定期杂交密度函数（PBE0+MBD）来评估X23基准的分子晶体集。我们表明，三聚体相互作用对于在1 kJ/mol之内的准确近似晶格能至关重要，也可能需要进一步改善晶格常数和细胞体积。最后，在单体和二聚体水平上已经很好地捕获了振动性能，从而可以在1 kJ/mol以内的室温下近似振动的自由能。
Accurate calculations of molecular crystals are crucial for drug design and crystal engineering. However, periodic high-level density functional calculations using hybrid functionals are often prohibitively expensive for relevant systems. These expensive periodic calculations can be circumvented by the usage of embedding methods in which for instance the periodic calculation is only performed at a lower-cost level and then monomer energies and dimer interactions are replaced by those of the higher-level method. Herein, we extend upon such a multimer embedding approach to enable energy corrections for trimer interactions and the calculation of harmonic vibrational properties up to the dimer level. We evaluate this approach for the X23 benchmark set of molecular crystals by approximating a periodic hybrid density functional (PBE0+MBD) by embedding multimers into less expensive calculations using a generalized-gradient approximation (GGA) functional (PBE+MBD). We show that trimer interactions are crucial for accurately approximating lattice energies within 1 kJ/mol and might also be needed for further improvement of lattice constants and hence cell volumes. Finally, vibrational properties are already very well captured at the monomer and dimer level, making it possible to approximate vibrational free energies at room temperature within 1 kJ/mol.
