# XANES

### From FEFF

* Standard *

XANES [xkmax xkstep estep]

The XANES card is used when a calculation of the near edge structure including the atomic background and absolute energies is desired. All parameters are optional, and are used to change the output energy mesh for the XANES calculation. XANES is not calculated unless the XANES card is present

The XANES calculation is currently limited to the (extended) continuum spectrum beyond the Fermi level. Thus bound states are not generally included; however, in molecules weakly bound states that are below the vacuum but above the muffin-tin zero will show up as resonances. The absolute energies are based on atomic total energy calculations using the Dirac-Fock-Desclaux atom code. The accuracy of this approximation varies from a few eV at low Z to a few hundred eV for very large Z.

- xkmax
- The maximum k value of the XANES calculation. If FMS calculations are being made, note that these are not accurate beyond about k = 6; for larger values of k, e.g. k = 20 with the path expansion, FMS must be turned off.
- xkstep
- This argument specifies the size of the output k grid far from the edge.
- estep
- This argument specifies the energy step of the grid at the edge.

The default values are xkmax = 8, xkstep = 0.07, and estep = ch/4+vi0/2, where vi0 is given by the EXCHANGE card

* finer grid for XANES calculation XANES 6.0 0.05 0.3