[Ifeffit] Simulation of ion xanes spectra using feff9

[Aurora Clark]

Hi;

I hope you don¹t mind me posting a question about feff9 to this list, but
the feff userlist is defunct.

I am trying to learn feff9 by reproducing the work in a JPCA recent paper
(JPCA 2011, 115, 2345). I have a calculated structure for U(H2O)8]4+ ion
that is nearly identical to that of the paper and so I am using that
structure.  I have been able to run several test cases for feff9 and I think
I have a reasonable understanding of the different cards in feff9 ­ however
there are definitely some particulars for these f-element ions that are
eluding me.


My primary question surround how to deal with ion charge

1. I have tried several options with the ion card, everything from the U
having a charge of 4 and the O-atoms zero, to partial charges like 2 and
­0.25. However, in each case I get errors that state:

ION:
 Expert option, please read documentation carefully and check your results.
 ION:
 Expert option, please read documentation carefully and check your results.
 U4+-8h2o

Now ­ if I run the calculation with no charges on the atoms everything
proceeds very smoothly. The manual states that charges typically should not
exceed 1 for an atom ­ but in a highly charged system what are you to do?

Thank you;
Aurora


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