Speaker
Description
PDFgui is a user-friendly graphical interface built on the PDFfit2 small-box modeling engine for the refinement of neutron and X-ray pair distribution function (PDF) data, enabling the extraction of nanoscale structural information from complex materials. By streamlining the setup, execution, and visualization of PDF refinements, PDFgui provides an accessible environment for organizing fits, performing sequential refinements, and comparing multiple structural models.
At its core, PDFfit2 is a flexible program and library for real-space refinement of crystal structures against PDF data. It enables fitting of three-dimensional structural models to experimental PDFs while accounting for key structural parameters, including lattice constants, atomic positions, anisotropic atomic displacement parameters, and correlated atomic motion. Experimental effects influencing the measured PDF can also be incorporated, and atomic coordinates and thermal parameters can be constrained according to the symmetry of arbitrary space groups, making the approach broadly applicable to both crystalline and nanostructured systems.
In this presentation, the overall PDFgui workflow and interface design will be introduced, along with its essential capabilities for small-box PDF analysis. The utility of the approach for investigating bulk materials with nanoscale heterogeneity will be illustrated through a recent example highlighting the detection of hidden local symmetry breaking in a high-performance thermoelectric material. In addition, typical use cases will be discussed, including co-refinement of multiple datasets, phase analysis, and sequential refinements across variables such as temperature, composition, and real-space fitting range.
PDFfit2 and PDFgui are freely available and continue to serve as widely used tools for real-space PDF analysis in materials research. The program can be downloaded from https://www.diffpy.org/products/pdfgui.html#installation
Tutorial files are available at
https://workshops.ill.fr/event/509/attachments/583/2603/PDFgui-tutorial-2022.zip
