We present PyXtal, a new package based on the Python programming language, used to generate structures with specific symmetry and chemical compositions for both atomic and molecular systems. This software provides support for various systems described by point, rod, layer, and space group symmetries. With only the inputs of chemical composition and symmetry group information, PyXtal can automatically find a suitable combination of Wyckoff positions with a step-wise merging scheme. Further, PyXtal can generate different dimensional organic crystals with molecules occupying both general and special Wyckoff positions, when the molecular geometry is given. Optionally, PyXtal also accepts user-defined parameters (e.g., cell parameters, minimum distances). In general, PyXtal serves two purposes: (1) it can be used to generate custom structures, (2) it can be interfaced with existing structure prediction codes that require the generation of random symmetric structures. In addition, we provide several utilities that facilitate the analysis of structures, including symmetry analysis, geometry optimization, and simulations of powder X-ray diffraction. Full documentation of PyXtal is available at \url{this https URL}.

中文翻译：

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PyXtal：用于晶体结构生成和对称性分析的 Python 库

我们展示了 PyXtal，这是一个基于 Python 编程语言的新包，用于为原子和分子系统生成具有特定对称性和化学成分的结构。该软件为由点、棒、层和空间群对称性描述的各种系统提供支持。只需输入化学成分和对称群信息，PyXtal 就可以通过逐步合并方案自动找到合适的 Wyckoff 位置组合。此外，当给出分子几何形状时，PyXtal 可以生成不同维度的有机晶体，其中分子占据一般和特殊的 Wyckoff 位置。可选地，PyXtal 还接受用户定义的参数（例如，单元格参数、最小距离）。一般来说，PyXtal 有两个用途：（1）它可以用来生成自定义结构，(2) 它可以与需要生成随机对称结构的现有结构预测代码接口。此外，我们提供了多种有助于结构分析的实用程序，包括对称性分析、几何优化和粉末 X 射线衍射模拟。PyXtal 的完整文档位于 \url{this https URL}。