Accurate prediction of structure and stability of molecular crystals is crucial in materials science and requires reliable modeling of long-range dispersion interactions. Semiempirical electronic structure methods are computationally more efficient than their ab initio counterparts, allowing structure sampling with significant speedups. We combine the Tkatchenko–Scheffler van der Waals method (TS) and the many-body dispersion method (MBD) with third-order density functional tight-binding (DFTB3) via a charge population-based method. We find an overall good performance for the X23 benchmark database of molecular crystals, despite an underestimation of crystal volume that can be traced to the DFTB parametrization. We achieve accurate lattice energy predictions with DFT+MBD energetics on top of vdW-inclusive DFTB3 structures, resulting in a speedup of up to 3000 times compared with a full DFT treatment. This suggests that vdW-inclusive DFTB3 can serve as a viable structural prescreening tool in crystal structure prediction.

中文翻译：

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具有多分散体包含在内的密度泛函紧密结合的分子晶体的结构和稳定性。

在材料科学中，准确预测分子晶体的结构和稳定性至关重要，并且需要对长程色散相互作用进行可靠的建模。半经验电子结构方法在计算上比其从头算方法更有效，从而可以显着加快结构采样的速度。通过基于电荷种群的方法，我们将Tkatchenko–Scheffler van der Waals方法（TS）和多体分散方法（MBD）与三阶密度泛函紧密结合（DFTB3）相结合。尽管可以低估可归因于DFTB参数化的晶体体积，但我们发现X23分子晶体基准数据库的总体性能良好。我们在包含vdW的DFTB3结构的基础上，通过DFT + MBD高能技术实现了准确的晶格能量预测，与完整的DFT处理相比，加速了3000倍。这表明包含vdW的DFTB3可以作为晶体结构预测中可行的结构预筛选工具。