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

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