xrdfit is a Python package for fitting the diffraction peaks in synchrotron X-ray diffraction (SXRD) and XRD spectra. It is intended as an easy to use tool for the quick analysis of individual and overlapping lattice plane peaks, to quantify the peak positions and profiles.
xrdfit uses the Python package lmfit for the underlying fitting. Features are included for selecting different ‘cakes’ of data and automating fitting over many spectra, to enable tracking of peaks as they shift throughout an experiment.
xrdfit is designed to be used by experimental researchers who need to process SXRD spectra but do not have a detailed knowledge of programming or fitting.
xrdfit is compatible with Python 3.6+.
Use pip to install the latest stable version of
pip install xrdfit
The current development version is available on github. To install use:
git clone --branch develop https://github.com/LightForm-group/xrdfit cd xrdfit python -m pip install .
This documentation is primarily an API reference, auto-generated from the docstrings in the source code.
The primary source of documentation for new users is a series of tutorial Jupyter Notebooks which are included with the source code. You can check out the tutorial notebooks online in your browser at Binder.
The code does not contain formal tests but almost all of the features are covered in the tutorial notebooks. If you can run these then you have installed xrdfit successfully!
The source and tutorial notebooks are available on the xrdfit GitHub page.
Comparison to other peak fitting tools¶
DAWN is a multipurpose framework, developed to deal with analysis of a whole range of datasets measured from beamline experiments. It is the most comparable tool we have come across in terms of its ability to do simple fits like those done by xrdfit.
Testing the fitting of a clear single peak for a dataset of 1000 spectra we find that DAWN typically takes 1-2 seconds per image and provides only limited information about the result of the fit as an output. DAWN only appears to allow fitting of a single peak at a time, fitting multiple peaks could mean running the same analysis each time for each peak. The automation of fitting in DAWN depends on identifying peak bounds using a point and click method within a GUI, which can’t be used as part of a reproducible analysis. We also found that the program crashed when attempting to load more than 1000 spectra for analysis.
For xrdfit, fitting of the same peak is much faster, on the order of 0.05 seconds per spectra. It is also possible to set up an analysis to fit multiple peaks simultaneously which greatly speeds the analysis of a full spectrum. Fitting is much more interactive, meaning that it is possible to more quickly review the fits and modify them if necessary. xrdfit can also easily deal with large datasets, containing many thousands of patterns.
MAUD can be used to fit peaks in diffraction spectra but uses a Rietveld refinement method to match a model of the beamline setup and material properties to the data. This method is extremely useful for calculating different material properties, such as the crystallographic texture. However, because MAUD uses a model of the unit cell to fit the data, there is some averaging of the overall fit and a larger error in the individual peak position and intensity.