[Ifeffit] Possible bug in atoms files generation by Artemis

[Matthew Marcus]

Just to put my bit in, I believe that the most significant advantage of higher FEFF versions for EXAFS analysis is that it results in
more reasonable values for E0 for high-Z elements.  I forget whether the issue is high-Z scatterer or absorber.  If you use any of the
common prescriptions for defining E0 with, say, Pt metal in FEFF6l, your fit will want large values of enot.  That said, I have not done
a real test by comparing FEFF8 and FEFF6 paths.  Has anyone done that?  It would be interesting to know what happens if you simulate a
k^n*chi(k) with one program and fit it with the other.
	mam

On 3/26/2013 1:10 PM, Ravel, Bruce wrote:
>
> This is more a documentation bug in the sense that I have not written any documentation explaining how to use Feff8 with Demeter.  What's more, I have not completely tested using Feff8 and there are probably still missing features.  I would not expect Feff8 to work completely to your satisfaction at this stage.
>
> Even once I get Feff8 support fully implemented, I have no intention of distributing a copy of the Feff8 executable with Demeter.  Indeed, I do not have the authority to do so.
>
> That said, you need to go to the File menu -> Preferences, the Feff->executable.  Change the value of that parameter to the location on your computer where the Feff8 executable can be found.  Demeter is not currently smart enough to choose a Feff executable according to how you selected to generate the feff.inp file.  It is entirely up to you to do  that correctly.
>
> Feff6 input files often work, in some sense, with the Feff8 executable.  Feff8 input files will not work with the feff6 executable.  That is the issue you are reporting as a bug.
>
> In closing, I'll say two things.  (1) Feff8 is not yet fully supported in Demeter -- use it at your own peril.  I will eventually get it fully implemented, but it is at this time near the top of my list of priorities.  (2) You should go back to the mailing list archives and find the last discussion about the relative merits of feff6 and feff8 for EXAFS analysis. I was then and remain now rather unconvinced that feff8 does anything substantive for you in the context of your EXAFS analysis.
>
> B
>
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 
 --
> *From:* ifeffit-bounces at millenia.cars.aps.anl.gov [ifeffit-bounces at millenia.cars.aps.anl.gov] on behalf of Devender [devend at rpi.edu]
> *Sent:* Tuesday, March 26, 2013 3:26 PM
> *To:* XAFS Analysis using Ifeffit
> *Subject:* [Ifeffit] Possible bug in atoms files generation by Artemis
>
> Hi,
>
> I ran updater for Demeter 0.9.15. I was using Artemis to calculate paths for Bi L3 in Bi2Te3. I saw now the option of using both (FEFF 6 and FEFF 8 style) for atoms. Previously, I was using only available option of FEFF6 style. When I tried to run atoms selecting FEFF 8, it generated atoms files but when I tried to run FEFF calculations it produced following errors.
>
> Error#1
> " Unknown keyword: "EDGE" at line:
>      EDGE      L3"
>
>
> Error#2
>    "Unknown keyword: "exchange" at line:
>      exchange"
>
> I worked around first error by replacing
>
>   "EDGE      L3
>   S02       1.0 "- which was generated by atoms when FEFF8 style is selected.
>
> with
> "HOLE      4   1.0" and deleting Exchange keyword from feff file. After making these edits in feff files, I was able to run FEFF without showing any errors. I have attached all the files with appropriate name.
>
> --
> Devender
> Graduate Student, Materials Science and Engineering
> Rensselaer Polytechnic Institute, Troy, NY
> Website <https://sites.google.com/site/devendermaun/>
>
>
>
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