Tasci Emre S, Elcoro Luis, Perez-Mato J Manuel, de la Flor Gemma, Aroyo Mois I
Physics Engineering Department, Hacettepe University, Ankara, Türkiye.
Departamento de Física, Facultad de Ciencia y Tecnología Universidad del Pais Vasco UPV/EHU Apartado 644 Bilbao Spain.
J Appl Crystallogr. 2024 Oct 1;57(Pt 5):1650-1666. doi: 10.1107/S1600576724008070.
is a free online program at the Bilbao Crystallographic Server (https://www.cryst.ehu.es/). It permits the exploration of all possible symmetries resulting from the distortion of a higher-symmetry parent structure, provided that the relation between the lattices of the distorted and parent structures is known. The program calculates all the subgroups of the parent space group which comply with this relation. The required minimal input is the space-group information of the parent structure and the relation of the unit cell of the distorted or pseudo-symmetric structure with that of the parent structure. Alternatively, the wavevector(s) observed in the diffraction data characterizing the distortion can be introduced. Additional conditions can be added, including filters related to space-group representations. The program provides very detailed information on all the subgroups, including group-subgroup hierarchy graphs. If a Crystallographic Information Framework (CIF) file of the parent high-symmetry structure is uploaded, the program generates CIF files of the parent structure described under each of the chosen lower symmetries. These CIF files may then be used as starting points for the refinement of the distorted structure under these possible symmetries. They can also be used for density functional theory calculations or for any other type of analysis. The power and efficiency of the program are illustrated with a few examples.
这是毕尔巴鄂晶体学服务器（https://www.cryst.ehu.es/）上的一个免费在线程序。它允许探索由更高对称性母结构畸变产生的所有可能对称性，前提是已知畸变结构与母结构晶格之间的关系。该程序计算符合此关系的母空间群的所有子群。所需的最小输入是母结构的空间群信息以及畸变或伪对称结构的晶胞与母结构晶胞的关系。或者，可以引入在表征畸变的衍射数据中观察到的波矢。可以添加其他条件，包括与空间群表示相关的滤波器。该程序提供了关于所有子群的非常详细的信息，包括群 - 子群层次图。如果上传母高对称结构的晶体学信息框架（CIF）文件，该程序会生成在每个选定的较低对称性下描述的母结构的CIF文件。这些CIF文件然后可以用作在这些可能对称性下精修畸变结构的起点。它们也可用于密度泛函理论计算或任何其他类型的分析。通过几个例子说明了该程序的功能和效率。
