On Friday 30 January 2009 08:49:36 am tony vitova wrote:
> Hi all,
> I am trying to fit Eu L3 edge EXAFS data of Eu complex whose structure is
> known (hopefully correct). The default feff6l in Artemis reports an error
>  “Hard tests failed in fovrg. Muffin-tin radius may be too large;
> coordination number too small“. When I run feff8.2, this error exchanges
> with the following message “The phase shift correction is accurate to
> k=19”. I guess that this is not a problem, because my data is until k equal
> 12 A^-1. However, the fit of the first shell (9O/9N) gives Eo equal to 13,
> which is unrealistic. This fit with paths calculated with feff6l gives
> reasonable Eo value. But the phase shifts seem to be calculated
> incorrectly. I will be very thankful for any hint! Thanks in advance


A quit bit of googling turned up this useful mailing list post from
John Rehr from a couple of years ago about the "Hard test fail" thing
in feff6:


That doesn't answer your question about feff8 however.  John or one of
his students would be better able to address that, however one might
be concerned that Feff has made a bad choice about which electrons to
consider as core electrons and which to consider as valence
electrons.  A bad choice there could confuse teh self-consistency

I think the bottom line is whether the rest of the results besides E0
make physical sense....



 Bruce Ravel  ------------------------------------ bra...@bnl.gov

 National Institute of Standards and Technology
 Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2
 Building 535A
 Upton NY, 11973

 My homepage:    http://xafs.org/BruceRavel
 EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/

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