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Charge disproportionation and XANES in FEFF



Hi all,

I am currently working on analyzing spectra from a material which the creators believe undergo charge disproportionation at a certain temperature; i. e. they believe Fe4+ --> Fe3+ + Fe5+. I am hoping to use FEFF8 to give me a qualitative feel for the kinds of changes that could be expected in the XANES spectrum if this occurs, but I am not sure how to do this.

The documentation for FEFF warns against using the ION card with the SCF card, since the SCF calculation will just redistribute the charge anyway. This makes sense, so I thought I'd try the calculation without the SCF card, even though I know that will reduce the accuracy of the simulation dramatically--after all, I'm just after some qualitative features. For the first calculation, I tried the case where all Fe was 4+, and arbitrarily divided all formal valence states by 10 for purposes of the ion card.

When I try it, however, FEFF gives me an error. I'm using FEFF 8.20x8, and have attached the FEFF.INP file and the output.

Most of my experience is in EXAFS, not XANES, so I really haven't tried anything like this before. I guess I have three questions:

1) How does one simulate charge disproportionation with FEFF?

2) Do XANES calculations without the SCF card have even qualitative validity, or are they completely pointless?

3) Why am I getting an error?

I look forward to reading the responses...

--Scott Calvin
Code 6344
Naval Research Lab
 * This feff.inp file generated by ATOMS, version 2.50
 * ATOMS written by and copyright (c) Bruce Ravel, 1992-1999

 * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- *
 *       total mu =     1032.8 cm^-1, delta mu =      541.1 cm^-1
 *       specific gravity =  5.339, cluster contains  119 atoms.
 * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- *
 *       mcmaster corrections:  0.00065 ang^2 and  0.812E-06 ang^4
 * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- *

 TITLE   name:     SrFeO3
 TITLE   formula:  SrFeO3
 TITLE   Simplistic based on SrTiO3

 HOLE 1   1.0     Fe K edge  (  7.112 keV), second number is S0^2

 *         mphase,mpath,mfeff,mchi
 CONTROL   1      1     1     1
 PRINT     1      0     0    0 0 3

 RMAX       6.76367

 *CRITERIA     curved   plane
 *DEBYE        temp     debye-temp
 *NLEG         8

 XANES

 POTENTIALS
 *   ipot   z  label
       0   26   Fe
       1    8   O
       2   38   Sr
       3   26   Fe

 ION 0 0.5
 ION 3 0.4
 ION 1 -0.2
 ION 2 0.2
% SCF 3.0

 ATOMS
   0.00000     0.00000     0.00000    0   Fe1              0.00000
  -1.95250     0.00000     0.00000    1   O1               1.95250
   0.00000     0.00000    -1.95250    1   O1               1.95250
   0.00000    -1.95250     0.00000    1   O1               1.95250
   0.00000     0.00000     1.95250    1   O1               1.95250
   0.00000     1.95250     0.00000    1   O1               1.95250
   1.95250     0.00000     0.00000    1   O1               1.95250
  -1.95250     1.95250    -1.95250    2   Sr1              3.38183
  -1.95250    -1.95250     1.95250    2   Sr1              3.38183
  -1.95250     1.95250     1.95250    2   Sr1              3.38183
  -1.95250    -1.95250    -1.95250    2   Sr1              3.38183
   1.95250     1.95250     1.95250    2   Sr1              3.38183
   1.95250    -1.95250    -1.95250    2   Sr1              3.38183
   1.95250     1.95250    -1.95250    2   Sr1              3.38183
   1.95250    -1.95250     1.95250    2   Sr1              3.38183
  -3.90500     0.00000     0.00000    3   Fe1              3.90500
   0.00000    -3.90500     0.00000    3   Fe1              3.90500
   0.00000     3.90500     0.00000    3   Fe1              3.90500
   0.00000     0.00000     3.90500    3   Fe1              3.90500
   0.00000     0.00000    -3.90500    3   Fe1              3.90500
   3.90500     0.00000     0.00000    3   Fe1              3.90500
  -3.90500     1.95250     0.00000    1   O1               4.36592
  -3.90500    -1.95250     0.00000    1   O1               4.36592
  -3.90500     0.00000     1.95250    1   O1               4.36592
  -3.90500     0.00000    -1.95250    1   O1               4.36592
  -1.95250    -3.90500     0.00000    1   O1               4.36592
  -1.95250     0.00000     3.90500    1   O1               4.36592
  -1.95250     3.90500     0.00000    1   O1               4.36592
  -1.95250     0.00000    -3.90500    1   O1               4.36592
   0.00000     1.95250    -3.90500    1   O1               4.36592
   0.00000     3.90500    -1.95250    1   O1               4.36592
   0.00000    -3.90500     1.95250    1   O1               4.36592
   0.00000    -3.90500    -1.95250    1   O1               4.36592
   0.00000     3.90500     1.95250    1   O1               4.36592
   0.00000    -1.95250    -3.90500    1   O1               4.36592
   0.00000     1.95250     3.90500    1   O1               4.36592
   0.00000    -1.95250     3.90500    1   O1               4.36592
   1.95250     3.90500     0.00000    1   O1               4.36592
   1.95250     0.00000    -3.90500    1   O1               4.36592
   1.95250     0.00000     3.90500    1   O1               4.36592
   1.95250    -3.90500     0.00000    1   O1               4.36592
   3.90500     1.95250     0.00000    1   O1               4.36592
   3.90500     0.00000    -1.95250    1   O1               4.36592
   3.90500    -1.95250     0.00000    1   O1               4.36592
   3.90500     0.00000     1.95250    1   O1               4.36592
  -3.90500     3.90500     0.00000    3   Fe1              5.52250
  -3.90500     0.00000     3.90500    3   Fe1              5.52250
  -3.90500    -3.90500     0.00000    3   Fe1              5.52250
  -3.90500     0.00000    -3.90500    3   Fe1              5.52250
   0.00000     3.90500     3.90500    3   Fe1              5.52250
   0.00000    -3.90500     3.90500    3   Fe1              5.52250
   0.00000     3.90500    -3.90500    3   Fe1              5.52250
   0.00000    -3.90500    -3.90500    3   Fe1              5.52250
   3.90500     0.00000    -3.90500    3   Fe1              5.52250
   3.90500     0.00000     3.90500    3   Fe1              5.52250
   3.90500    -3.90500     0.00000    3   Fe1              5.52250
   3.90500     3.90500     0.00000    3   Fe1              5.52250
  -5.85750     0.00000     0.00000    1   O1               5.85750
  -3.90500     1.95250    -3.90500    1   O1               5.85750
  -3.90500    -1.95250    -3.90500    1   O1               5.85750
  -3.90500    -1.95250     3.90500    1   O1               5.85750
  -3.90500    -3.90500     1.95250    1   O1               5.85750
  -3.90500     3.90500    -1.95250    1   O1               5.85750
  -3.90500     3.90500     1.95250    1   O1               5.85750
  -3.90500    -3.90500    -1.95250    1   O1               5.85750
  -3.90500     1.95250     3.90500    1   O1               5.85750
  -1.95250    -3.90500    -3.90500    1   O1               5.85750
  -1.95250     3.90500    -3.90500    1   O1               5.85750
  -1.95250     3.90500     3.90500    1   O1               5.85750
  -1.95250    -3.90500     3.90500    1   O1               5.85750
   0.00000    -5.85750     0.00000    1   O1               5.85750
   0.00000     0.00000    -5.85750    1   O1               5.85750
   0.00000     5.85750     0.00000    1   O1               5.85750
   0.00000     0.00000     5.85750    1   O1               5.85750
   1.95250     3.90500    -3.90500    1   O1               5.85750
   1.95250     3.90500     3.90500    1   O1               5.85750
   1.95250    -3.90500     3.90500    1   O1               5.85750
   1.95250    -3.90500    -3.90500    1   O1               5.85750
   3.90500     1.95250    -3.90500    1   O1               5.85750
   3.90500     1.95250     3.90500    1   O1               5.85750
   3.90500    -3.90500     1.95250    1   O1               5.85750
   3.90500    -1.95250    -3.90500    1   O1               5.85750
   3.90500     3.90500     1.95250    1   O1               5.85750
   3.90500    -1.95250     3.90500    1   O1               5.85750
   3.90500    -3.90500    -1.95250    1   O1               5.85750
   3.90500     3.90500    -1.95250    1   O1               5.85750
   5.85750     0.00000     0.00000    1   O1               5.85750
  -5.85750    -1.95250    -1.95250    2   Sr1              6.47571
  -5.85750     1.95250    -1.95250    2   Sr1              6.47571
  -5.85750    -1.95250     1.95250    2   Sr1              6.47571
  -5.85750     1.95250     1.95250    2   Sr1              6.47571
  -1.95250    -5.85750    -1.95250    2   Sr1              6.47571
  -1.95250    -1.95250     5.85750    2   Sr1              6.47571
  -1.95250     5.85750     1.95250    2   Sr1              6.47571
  -1.95250    -1.95250    -5.85750    2   Sr1              6.47571
  -1.95250    -5.85750     1.95250    2   Sr1              6.47571
  -1.95250     5.85750    -1.95250    2   Sr1              6.47571
  -1.95250     1.95250    -5.85750    2   Sr1              6.47571
  -1.95250     1.95250     5.85750    2   Sr1              6.47571
   1.95250    -5.85750     1.95250    2   Sr1              6.47571
   1.95250    -1.95250    -5.85750    2   Sr1              6.47571
   1.95250     1.95250     5.85750    2   Sr1              6.47571
   1.95250    -1.95250     5.85750    2   Sr1              6.47571
   1.95250     5.85750    -1.95250    2   Sr1              6.47571
   1.95250     1.95250    -5.85750    2   Sr1              6.47571
   1.95250     5.85750     1.95250    2   Sr1              6.47571
   1.95250    -5.85750    -1.95250    2   Sr1              6.47571
   5.85750     1.95250     1.95250    2   Sr1              6.47571
   5.85750    -1.95250    -1.95250    2   Sr1              6.47571
   5.85750    -1.95250     1.95250    2   Sr1              6.47571
   5.85750     1.95250    -1.95250    2   Sr1              6.47571
  -3.90500     3.90500    -3.90500    3   Fe1              6.76366
  -3.90500     3.90500     3.90500    3   Fe1              6.76366
  -3.90500    -3.90500    -3.90500    3   Fe1              6.76366
  -3.90500    -3.90500     3.90500    3   Fe1              6.76366
   3.90500    -3.90500    -3.90500    3   Fe1              6.76366
   3.90500    -3.90500     3.90500    3   Fe1              6.76366
   3.90500     3.90500    -3.90500    3   Fe1              6.76366
   3.90500     3.90500     3.90500    3   Fe1              6.76366
 END
Feff 8.20x8
  XANES:
 ION:
 Expert option, please read documentation carefully and check your results.
 ION:
 Expert option, please read documentation carefully and check your results.
 ION:
 Expert option, please read documentation carefully and check your results.
 ION:
 Expert option, please read documentation carefully and check your results.
 name:     SrFeO3
 formula:  SrFeO3
 Simplistic based on SrTiO3
 Calculating potentials ...
    free atom potential and density for atom type    0
    free atom potential and density for atom type    1
    free atom potential and density for atom type    2
    free atom potential and density for atom type    3
    initial state energy
    overlapped potential and density for unique potential    0
    overlapped potential and density for unique potential    1
    overlapped potential and density for unique potential    2
    overlapped potential and density for unique potential    3
    free atom potential and density for atom type    0
    free atom potential and density for atom type    1
    free atom potential and density for atom type    2
    free atom potential and density for atom type    3
    initial state energy
    overlapped potential and density for unique potential    0
    overlapped potential and density for unique potential    1
    overlapped potential and density for unique potential    2
    overlapped potential and density for unique potential    3
    muffin tin radii and interstitial parameters
 iph, rnrm(iph)*bohr, rmt(iph)*bohr, folp(iph)
    0  1.32388E+00  1.22575E+00  1.15000E+00
    1  1.10126E+00  1.04775E+00  1.13528E+00
    2  1.83921E+00  1.80558E+00  1.04543E+00
    3  1.33138E+00  1.22889E+00  1.15000E+00
              Core-valence separation
WARNING: fatal error in subroutine corval. Try
  to reduce ca1 in SCF card. If does not help,
SEND bug report to AUTHORS
CORVAL-1
 Press RETURN to quit the program.