EXAFS

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Data Analysis

Setting up

Install feff. Follow the link for the instructions.

Install the full 'Demeter' package, that includes the 'Athena' program. It only works well in Windows 64-bits.

Pre-processing

For each structure you want to analyze:

• Create a folder.
• Put the VASP output in that folder.
• Convert the structure to a .cif file.
• Convert the .cif to feff.inp using this page: http://millenia.cars.aps.anl.gov/webatoms/

Processing

Run sequentially these commands on a terminal; feff must be already installed. More information can be found in INSTALL.md, inside the feff85exafs-master folder.

feff8l_rdinp
feff8l_pot
feff8l_xsph
feff8l_pathfinder
feff8l_genfmt
feff8l_ff2x

Post-processing

These steps should be followed in Athena, from your Virtual machine.

• Open Athena.
• Import chi.dat.
• Select chi(k) as data type.
• Click in "replot".
• Select the element and edge. (i.e., Pd, K-edge).
• Edit k-range [3.0;14.0], dK=1.
• Select plotting k-weights: 3.
• Apply a forward Fourier transform.
• Change plot to R-space, Magnitude-Magnitude. Select and unselect "real part" to update the graph. This will generate a plot |chi(R)| in Å^(-4) as a function of the radial distance in Å.
• To change the units of chi(R), change the k-weights.
• In the main window, clic on file > save current group as > chi(R).
• Save the file as .dat inside your Windows virtual machine. Then move to the shared folder to do the analysis.
• You can now do a fancy plot in Origin, showing the chi(R) data you got from Athena.