PDFfit2 and PDFgui: computer programs for studying nanostructure in crystals

TLDR

PDFfit2 is a C++ library and program that refines crystal structures in real space by fitting a theoretical 3D model to atomic pair distribution function data, accounting for lattice constants, atomic positions, anisotropic displacement parameters, correlated motion, experimental factors, and symmetry constraints, and is accessible via Python and a graphical interface PDFgui. PDFfit2 and PDFgui are freely available on the Internet.

Abstract

PDFfit2 is a program as well as a library for real-space refinement of crystal structures. It is capable of fitting a theoretical three-dimensional (3D) structure to atomic pair distribution function data and is ideal for nanoscale investigations. The fit system accounts for lattice constants, atomic positions and anisotropic atomic displacement parameters, correlated atomic motion, and experimental factors that may affect the data. The atomic positions and thermal coefficients can be constrained to follow the symmetry requirements of an arbitrary space group. The PDFfit2 engine is written in C++ and is accessible via Python, allowing it to inter-operate with other Python programs. PDFgui is a graphical interface built on the PDFfit2 engine. PDFgui organizes fits and simplifies many data analysis tasks, such as configuring and plotting multiple fits. PDFfit2 and PDFgui are freely available via the Internet.