"Hard tests failed in fovrg"
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 Tonya
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
Tonya, 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: http://millenia.cars.aps.anl.gov/pipermail/ifeffit/2005-October/002080.html 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 calculation. I think the bottom line is whether the rest of the results besides E0 make physical sense.... B -- Bruce Ravel ------------------------------------ bravel@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/
Hi Everyone, If you ever encounter problems like this, please attach a feff.inp so we and others can duplicate and troubleshoot the problem. Thanks. Cheers, John
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
participants (3)
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Bruce Ravel -
John J. Rehr -
tony vitova