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Manuscript Title: Fourier analysis of EXAFS and XANES data: a self-contained Fortran program-package: the third version.
Authors: N. Aldea, E. Indrea
Program title: EXAFS (13,23,33,43,53,63)
Catalogue identifier: ACUF_v3_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 60(1990)145
Programming language: Fortran.
Computer: CORAL 4030.
Operating system: RSX-11M.
RAM: 61K words
Word size: 16
Peripherals: disc.
Keywords: Fourier analysis, Discret fourier Transform, Xanes, Exafs, Spectroscopy, Absorption, Scattering, Solid state physics, Local structure, Electronic transition, Surface.
Classification: 7.2.

Nature of problem:
This paper is a third version of the program package by Aldea and Indrea. The present version has, in addition, the possibility to process the XANES spectrum based on an improved smoothing procedure in order to extract more informations by second derivative analysis. The true position of the peaks radial distribution function are obtained by determining the phase shift function. This function can be obtained by three distinct methods.

Solution method:
THe smoothing and interpolation of incident and transmitted X-ray intensity-energy function is done by 3rd order piecewise polynomial functions. The XANES function, its first and second derivative and the absorption coefficients mu0(k) and mu(k) were determined by cubic splines in the least squares sense. The direct and inverse Fourier transform of EXAFS function was performed by Filon's algorithm or by Cooley-Tukey's algorithm. The phase shift function was obtained by linear, quadratic approximation or Newton's interpolation formula for unequally spaced values of the wave vector. The best fit values of structural parameters were computed by means of iterative least squares linear Taylor differential-correction technique.

Running time:
The new test case required 10 min execution time.