We present Ogre, an open-source code for generating surface slab models from bulk molecular crystal structures. Ogre is written in Python and interfaces with the FHI-aims code to calculate surface energies at the level of density functional theory (DFT). The input of Ogre is the geometry of the bulk molecular crystal. The surface is cleaved from the bulk structure with the molecules on the surface kept intact. A slab model is constructed according to the user specifications for the number of molecular layers and the length of the vacuum region. Ogre automatically identifies all symmetrically unique surfaces for the user-specified Miller indices and detects all possible surface terminations. Ogre includes utilities to analyze the surface energy convergence and Wulff shape of the molecular crystal. We present the application of Ogre to three representative molecular crystals: the pharmaceutical aspirin, the organic semiconductor tetracene, and the energetic material HMX. The equilibrium crystal shapes predicted by Ogre are in agreement with experimentally grown crystals, demonstrating that DFT produces satisfactory predictions of the crystal habit for diverse classes of molecular crystals.

中文翻译：

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Ogre：用于分子晶体表面生成的Python软件包，可用于表面能和晶体习惯预测。

我们介绍Ogre，这是一个用于从本体分子晶体结构生成表面平板模型的开源代码。Ogre用Python编写，并与FHI-aims代码连接，以在密度泛函理论（DFT）级别上计算表面能。Ogre的输入是本体分子晶体的几何形状。从主体结构上切下表面，并使表面上的分子保持完整。根据用户指定的分子层数和真空区域长度来构造平板模型。Ogre会自动为用户指定的Miller索引识别所有对称唯一的表面，并检测所有可能的表面终止。Ogre包含用于分析表面能量会聚和分子晶体的Wulff形状的实用程序。我们介绍Ogre在三种代表性分子晶体上的应用：药物阿司匹林，有机半导体并四苯和高能材料HMX。Ogre预测的平衡晶体形状与实验生长的晶体一致，这表明DFT可以针对各种类型的分子晶体产生令人满意的晶体习性预测。