The MXAN program performs a quantitative analysis of the XANES energy range, i.e. from the edge up to 200 eV. This is based on a comparison between experimental data and many theoretical spectra that are calculated by varying selected structural parameters of an initial putative structure, i.e. a well defined initial geometrical configurations around the absorber. Hundreds of different geometrical configurations are needed to obtain the best fit of the experimental data. The best fit condition is reached in a reasonable time, typically few hours for a molecular systems. The optimization in the parameter space is achieved by the minimization of the square residual function ( R_sq ) in the parameter space. The calculations are performed in the energy space without involving any Fourier-transform algorithm; polarized spectra can be easily analysed because the calculations are performed within the full multiple scattering approach.
Recently, MXAN of extracting the local structural information available in the XANES spectra has been developed in the framework of the multiple scattering theory and successfully applied to the analysis of several system, both in solid and liquid state.As the newest progress we have done in the MXAN procedure, in particular for what concerns the phenomenological broadening and the electronic charge fitting.
We have also implemented parallelization on MXAN code by MPI library for both energy points and annealing for no-structure parameters. This approach reduce the computer time of a factor ≈ 10 ( our cluster contains 14 nodes but the computer times scales with the number of nodes ) and at the same time increase the accuracy of the method.