Scott,
This can be fixed by editing the feff.inp file to remove the Fe potential 1, but that's not enough--the oxygen scatterers then have to have their potential renumbered to 1 to make things work. That's a lot of work to do what should be simple.
So I vote for changing the way Artemis works in such circumstances so that less editing is needed: if the absorbing atom is not present in the scattering list, then it shouldn't have a second entry in the potential list.
I second this vote, since I also have had this same problem. New users could become quickly disgruntled by the Fatal Error message when attempting to put in simple systems or just by choosing a short cluster distance to only include the first shell in the FEFF calculation. At a minimum, it would be nice if Artemis trapped this error and reported a more friendly popup error message. Dave _________________________________ David Barton, PhD. The Dow Chemical Company Catalysis R&D