Symmetry-mode analysis for local structure investigations using pair distribution function data
Symmetry-mode analysis for local structure investigations using pair distribution function data
复制标题
使用对分布函数数据进行局部结构研究的对称模式分析
DOI：
10.1107/s1600576723005794
复制
发表时间：
2023
影响因子：
6.1
通讯作者：
Frandsen, Benjamin A.
中科院分区：
文献类型：
--
作者：
Hamilton, Parker K.;Moya, Jaime M.;Hallas, Alannah M.;Morosan, E.;Baral, Raju;Frandsen, Benjamin A.
对称性自适应失真模式提供了一种描述源自更高对称性母相的失真结构的自然方式。结构的细化使用的衍射数据的平均晶体结构的Rietveld细化作为拟合变量的模振幅已被用于至少十年，最近，这种方法也被用于调查的本地结构使用真实空间对分布函数（PDF）的数据。在这里，通过成功地将这种方法应用于两种局部材料，进一步证明了对PDF数据进行双模态拟合的价值：TiSe 2，其中检测到由电荷密度波的形成驱动的细微但长范围的结构畸变，以及MnTe，其中大但高度局部化的结构畸变的特征在于Te原子的双模态降低位移。该分析是使用DiffPy框架内的完全开源代码通过为这项工作开发的两个软件包进行的：isopydistorts，它为ISODISTORT网络应用程序提供了一个可脚本化的接口，用于群理论计算，以及isopytools，它将ISODISTORT输出转换为DiffPy兼容的格式，用于随后的拟合和分析。这些发展通过实现高通量分析和消除对任何商业软件的需求，扩大了适应性PDF分析的潜在影响。
Symmetry-adapted distortion modes provide a natural way of describing distorted structures derived from higher-symmetry parent phases. Structural refinements using symmetry-mode amplitudes as fit variables have been used for at least ten years in Rietveld refinements of the average crystal structure from diffraction data; more recently, this approach has also been used for investigations of the local structure using real-space pair distribution function (PDF) data. Here, the value of performing symmetry-mode fits to PDF data is further demonstrated through the successful application of this method to two topical materials: TiSe2, where a subtle but long-range structural distortion driven by the formation of a charge-density wave is detected, and MnTe, where a large but highly localized structural distortion is characterized in terms of symmetry-lowering displacements of the Te atoms. The analysis is performed using fully open-source code within the DiffPy framework via two packages developed for this work: isopydistort, which provides a scriptable interface to the ISODISTORT web application for group theoretical calculations, and isopytools, which converts the ISODISTORT output into a DiffPy-compatible format for subsequent fitting and analysis. These developments expand the potential impact of symmetry-adapted PDF analysis by enabling high-throughput analysis and removing the need for any commercial software.