XFIT GitHub links

xfit source code :
average-wxwin :

The XFIT package of codes (AVERAGE, SPLINE, XFIT, GRAPH) was written in Sydney the 1990s by Dr Paul Ellis under the supervision of Prof. Hans Freeman. The package contains some useful functionality for data reduction (WSIWYG aspects) and especially for curve-fitting of EXAFS data including geometrical constraints/restraints and two-site modelling. However the code for most parts has not been supported for many years and some parts (SPLINE) cannot run on later than Windows XP service pack 1. In addition, XFIT only supports the use of FEFF4 and FEFF6.

The code is now released into the public domain through the following GitHub links. Rather than wishing for an updated version of XFIT, instead we hope that active programmers in the community will co-opt useful sections of code to incorporate the most treasured aspects of the software into their own packages.

Please let us know if you are doing so by emailing Hugh Harris ( ) with XFIT in the title. James Hester has some experience with the code and has agreed to answer some questions at .



The GNXAS package is and advanced software for EXAFS data analysis based on multiple-scattering (MS) calculations and a rigorous fitting procedure of the raw experimental data.
GNXAS2: A web environment for advanced XAS data-analysis

The main characteristic of the software are:
atomic phase shifts calculations in the muffin-tin approximation based on atom self-consistent relativistic calculations. Account for the neighbors is taken.
Inclusion of inelastic losses through complex Hedin-Lundqvist potential.
Calculation of MS signals associated with two, three, and four atom configurations using advanced algorithms.

Use of an advanced fitting procedure that allows:
to fit simultaneously any number of spectra containing any number of edges, to use directly the raw data without any pre-analysis, to account for complex background multi-electron excitation features, to use various model peaks for the pair, triplet and quadruplet distribution functions, including non Gaussian models and extremal cases.

In all cases absolute parameters can be fitted,to treat liquid phase or disordered systems and extract reliable g(r) functions in the short range, to perform a rigorous statistical error analysis and plot two-dimensional correlation maps, To provide a flexible scientific tool for EXAFS data analysis where the user has access to every stage of the calculation. GNXAS is not a black box. Full modularity than makes easy to interface parts of the GNXAS software with other available software.

Its flexibility and advanced characteristics are essential to perform a modern EXAFS data-analysis and to extract accurately all the valuable information contained in your data.




FitIt is a free software to fit spectra using multidimensional interpolation approximation. It works under 32-bit Microsoft Windows operation systems. The main field of applications is quantitative determination of the local atomic structure parameters on the basis of fitting of X-ray absorption near edge structure (XANES). The algorithm of multidimensional interpolation of the spectrum as a function of structural parameters allows to minimize the number of time-consuming calculations required to find optimal values of the parameters.
The main program FitIt.exe has visual interface and consist of two main parts:

  • Tool to construct multidimensional interpolation of the spectrum as a function of a few parameters.
  • Subroutine for multidimensional fitting of the spectrum. It allows to find the set of parameters which corresponds to the minimal discrepancy between interpolated and experimental spectra

The program allows to use any external program for calculations of the spectrum and only small converters are needed to generate input files and read output files of any program of the user. At the moment converters for compatibility with FEFF8 and FDMNES are distributed in the FitIt package.

Also you can use any program for transformation of the geometry of your cluster. In the FitIt distributive you will find program Prot2005, which allows to perform lots of types of geometry transformations.



FEFF is an automated program for ab initio multiple scattering calculations of X-ray Absorption Fine Structure (XAFS) and X-ray Absorption Near-Edge Structure (XANES) spectra for clusters of atoms. The code yields scattering amplitudes and phases used in many modern XAFS analysis codes, as well as various other properties.

  • FEFF 9: New Release Info Here
  • FEFF 8: The newest version is FEFF8 (Version 8.40). FEFF 8 improves over previous versions of FEFF by including self consistent calculation of potentials to provide charge transfer and a more accurate estimate of the Fermi level. It also includes full multiple scattering calculations to improve XANES calculations, where multiple scattering expansions can fail to converge. FEFF 8 can output the angular momentum projected density of states, x-ray emission spectra and x-ray scattering amplitudes. The improvements in FEFF 8.40 simplify spin-dependent calculations and can include improved treatment of core-hole and local field effects. FEFF8 now includes JFEFF, a graphical front-end for FEFF 8.4.
  • FEFF 7: Relativistic version of FEFF 6 including polarization.
  • FEFF 6: High-order multiple-scattering EXAFS/XANES code.
  • ATOMS: Generates input files, feff.inp, for crystalline materials which are suitable for FEFF5 and higher (included with FEFF).