[Ifeffit] HELP! EXAFS calculation for "+2" charged molecule

["Dr. Dariusz A. Zając"]

as I remember,  is written that feff underestimates ion's charge 5-10 
times.
ION {no. of ion}  {its ionization}
below I cite the information from JFeff help card:


***
  The ION card ionizes all atoms with unique potential index ipot. 
Negative values and non-integers are permitted, however ionicities 
larger than 2 and less than  -1 often yield unphysical results. Our 
experience with charge transfers using the SCF card suggests values for 
ionization about 5-10 times smaller than the formal oxidation state. The 
ION card is probably not needed if the potential is self-consistent. 
However, it can be used to put some total charge on a cluster. In this 
case we suggest using the same ionicity for all atoms in the cluster 
(i.e. total ionization divided by number of atoms). For example, for 
diatomics like Br2, the fully relaxed configuration has a formal 
ionization of 1 on the scattering atom. Because of charge transfer, the 
actual degree of ionization is much smaller. In non-self-consistent 
calculations the default (non-ionized) scattering potentials are often 
superior to those empirically ionized, and the results should be checked 
both ways. If ION is omitted, the atoms are not ionized by default.
   * Simulates effective ionization for formal valence state +1
   * ipot, ionization
   ION  1  0.2
***

W dniu 12-01-16 23:39, YOON Zin Seok pisze:
> Dear FEFF users,
>
> Hi, I am using FEFF9. I would like to calculate EXAFS spectrum of “+2”
> charged molecule.
>
> According to the manual “feff90_users_guide.pdf”, in pages 33-34, I
> thought maybe I ccould use ION card.  In page 34, in “ION 1 0.2”, what do
> “1” and “0.2” mean?
>
> Can you help me?
>
> Thank you.
>
> Zin
>
>
> _______________________________________________
> Ifeffit mailing list
> Ifeffit at millenia.cars.aps.anl.gov
> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
>