diffpy.pdffit2 documentation

diffpy.pdffit2 - PDFfit2 - real space structure refinement program.

Software version 1.5.1.
Last updated February 07, 2025.

The diffpy.pdffit2 package provides functions for the calculation and refinement of atomic Pair Distribution Functions (PDF) from crystal structure models. It is used as a computational engine by PDFgui. All refinements possible in PDFgui can be done by writing python scripts directly with diffpy.pdffit2, although less conveniently and with a fair knowledge of Python. However, we recommend using diffpy-cmi for carrying out more advanced, python-scripted refinements of nanostructure.

The PDFfit2 package includes an extension for the interactive IPython shell, these days commonly used within Jupyter notebooks, which tries to mimic the old PDFFIT program. To start IPython with this extension and also with plotting functions enabled, use

ipython --ext=diffpy.pdffit2.ipy_ext --pylab

The IPython extension is suitable for interactive use, however refinement scripts should be preferably written as a standard Python code. This is more reliable and needs only a few extra statements.

Authors

This code was derived from the first PDFFIT program written by Thomas Proffen and Simon Billinge, which was a FORTRAN implementation of the original “Real-space Rietveld” code written by Simon Billinge (Billinge, S. J. L. “Real-space Rietveld: full profile structure refinement of the atomic pair distribution function”. In: Local Structure from Diffraction. Ed. by S. J. L. Billinge and M. F. Thorpe. New York: Plenum, 1998, p. 137). The sources were converted to C++ by Jacques Bloch and then extensively hacked, extended and purged from most glaring bugs by Chris Farrow and Pavol Juhas. This code is currently maintained as part of the DiffPy project to create python modules for structure investigations from diffraction data.

The DiffPy team is located in the Billinge-group at the Applied Physics and Applied Mathematics Department of the Columbia University in New York. Previous significant contributors to this code were made by

Pavol Juhas, Chris Farrow, Jacques Bloch, Wenduo Zhou

with more recent contributions from Billinge-group members. For a more detailed list of contributors see https://github.com/diffpy/diffpy.pdffit2/graphs/contributors.

Reference

If you use this program for a scientific research that leads to publication, we ask that you acknowledge use of the program by citing the following paper in your publication:

C. L. Farrow, P. Juhás, J. W. Liu, D. Bryndin, E. S. Božin, J. Bloch, Th. Proffen and S. J. L. Billinge, PDFfit2 and PDFgui: computer programs for studying nanostructure in crystals (https://stacks.iop.org/0953-8984/19/335219), J. Phys.: Condens. Matter, 19, 335219 (2007)

Installation

Please see the README file included with the distribution.

Table of contents

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