Francisco, The feffNNNN.dat file tells you the interatomic distance used in the file in the header right below the line of dashes. Feff explains the contents of the feffNNNN.dat files here: http://leonardo.phys.washington.edu/feff/wiki/index.php?title=FEFF_Variables and here: http://leonardo.phys.washington.edu/feff/wiki/index.php?title=FEFF_Output_fi... Ifeffit explains its Fourier transforms here: http://cars.uchicago.edu/~ifeffit/refman/node77.html Chapter 6 of this document explains how Ifeffit constructs the chi(k) function from the feffNNNN.dat file, following the explanation in the Feff document: http://cars.uchicago.edu/~newville/feffit/feffit.pdf Artemis' plotting of phase corrected plots is explained here: http://bruceravel.github.io/demeter/artug/path/plot.html#phasecorrectedplots In truth, you're question was readily answered with Google and some patience. We're happy to answer questions here on the mailing list, but it is quite clear that you didn't try very hard to solve your own problem. B On Thursday, May 23, 2013 06:15:09 PM Francisco Garcia wrote:

Dear all,

Can an experienced user kindly explain how to obtain the phase shift correction to the radial distance corresponding to FFT(chi(k)). From my chi(k) computation, I have several feff*.dat files (feff0001.dat, feff0002.dat,...............,feff00128.dat) because I have 128 paths. How do I use this information and IFEFFIT to compute the shifted spectrum?

Thank you.

-- Bruce Ravel ------------------------------------ bravel@bnl.gov National Institute of Standards and Technology Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2 Building 535A Upton NY, 11973 Homepage: http://xafs.org/BruceRavel Software: https://github.com/bruceravel