Open AccessMXAN : a new software procedure to perform geometrical fitting of experimental XANES spectra
Author(s) -
Benfatto M.,
CongiuCastellano A.,
Daniele A.,
Della Longa S.
Publication year - 2001
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049500015338
Subject(s) - xanes , spectral line , tetrahedron , chemistry , function (biology) , distortion (music) , cross section (physics) , scattering , computational physics , atomic physics , molecular physics , physics , crystallography , optics , quantum mechanics , amplifier , optoelectronics , cmos , evolutionary biology , biology
A new software procedure, MXAN , to fit experimental XANES spectra is presented here. The method is based on the comparison between the experimental spectrum and several theoretical calculations generated by changing the relevant geometrical parameter of the site around the absorbing atom. The x‐ray photoabsorption cross section is calculated using the general multiple‐scattering scheme, utilizing a complex Hedin‐Lunqvist energy‐dependent potential to describe the exchange correlation interaction. Our method has been applied to the study of geometrical environment of the tetrahedral zinc site of the protein superoxide dismutase (SOD). The experimental Zn K‐edge XANES spectrum has been fitted in the space of the first shell coordination parameters (ligand distances and angles) following the behavior of the chi‐square as a function of the local distortion from the starting crystallographic structure. The recovered structure is found to be independent on the starting conditions, showing the theoretical uniqueness of the structural solution. Strengths and limitations of the application to real systems are also discussed.