## INTERSTITIAL

inters vtot

The construction of the interstitial potential and density may be changed by using this card. . ipot=1 might be useful when only the surroundings of the absorbing atom are specified in feff.inp'. irmt and irav are described only for completeness, and use of nonzero values is strongly discouraged.
ipot

potential index. ipot defines how to find the interstitial potential. ipot=0 (default): the interstitial potential is found by averaging over the entire extended cluster in feff.inp'. ipot=1 : the interstitial potential is found locally around the absorbing atom.
irav

also changes how the interstitial potential is found. irav=0 (default): the equation for V is constructed at rav=rnrm. irav=1 : at rav=(rmt +rnrm)/2. irav=2 : at rav=rmt, where rmt is the muffin-tin radius and rnrm is the Norman radius. irmt apparently does not exist in the code
irmt

irmt=0 (default): Norman prescription for mt radii. irmt=1 : Matching point prescription for mt radii (do not use).
vtot

the volume per atom normalized by ratmin (vtot=(volume per atom)/ratmin), where ratmin is the shortest bond for the absorbing atom. This quantity defines the total volume (needed to calculate the interstitial density) of the extended cluster specified in feff.inp'. If vtot then the total volume is calculated as a sum of Norman sphere volumes. Otherwise, , where nat is the number of atoms in an extended cluster. Thus vtot=1.0 is appropriate for cubic structures, such as NaCl. The INTERSTITIAL card may be useful for open systems (e.g. those which have ZnS structure).

  * improve interstitial density for ZnS structures.
* vtot = (unit_cell_volume/number_of_atoms_in_unit_cell)/ratmin**3)=1.54
INTERSTITIAL  0 1.54
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