The pypadf package: computing the pair angle distribution function from fluctuation scattering data

• Published in: Journal of applied crystallography Vol. 57; no. 3; pp. 877 - 884
• Main Authors: Martin, Andrew V., Adams, Patrick, Binns, Jack
• Format: Journal Article
• Language: English
• Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England International Union of Crystallography 01.06.2024; Blackwell Publishing Ltd
• Subjects: Computer Programs; Correlation; Diffraction; Distribution functions; fluctuation electron microscopy; fluctuation X‐ray scattering; Ion beams; pair angle distribution function; Scattering; Software; X‐ray cross‐correlation analysis; pair angle distribution function; software; X-ray cross-correlation analysis; fluctuation electron microscopy; fluctuation X-ray scattering
• ISSN: 1600-5767; 0021-8898; 1600-5767
• DOI: 10.1107/S1600576724002796

The pair angle distribution function (PADF) is a three‐ and four‐atom correlation function that characterizes the local angular structure of disordered materials, particles or nanocrystalline materials. The PADF can be measured using X‐ray or electron fluctuation diffraction data, which can be collected by scanning or flowing a structurally disordered sample through a focused beam. It is a natural generalization of established pair distribution methods, which do not provide angular information. The software package pypadf provides tools to calculate the PADF from fluctuation diffraction data. The package includes tools for calculating the intensity correlation function, which is a necessary step in the PADF calculation and also the basis for other fluctuation scattering analysis techniques. A Python‐based software package is presented that can compute the pair angle distribution function from X‐ray or electron fluctuation scattering data of disordered materials.