[Ifeffit] A problem Using FEFF8
Joshua Kas
joshua.j.kas at gmail.com
Thu Mar 25 02:06:17 CDT 2010
Hi Qui Nan,
There are several other parameters to the SCF card that may help.
Try the following,
* SCF rscf lscf niter ca nmix
SCF 8.0 0 30 0.05 0
ca is the convergence factor in the Broyden algorithm. A lower value of ca
will stabilize the SCF, but cause slower convergence. nmix is the number of
iterations using the mixing algorithm before starting the Broyden algorithm.
I have found that this is usually where the bad counts problem occurs, which
is why I set it to 0. If this still doesn't work, try other values for the
ca and nmix parameters.
I have found that changing the ca and nmix parameters will usually (not
always) fix the problem.
Please email the list again if you continue to have problems.
Cheers,
Josh Kas
> Dear Mr. Bruce,
> My name is QIU Nan, I am a student from Institute of High Energy
> Physics, Chinese Academy of Science.
> I encountered a preblem When I calculated O K edge of cerium oxide(CeO2)
> using FEFF8. FEFF found bad counts: Occupation number in getorb is 4.000
> , then FEFF repeated pteration again and again. The attached files are
> feff.inp I used and log1.dat that FEFF generated. Would you so kind to help
> me to finish this calculation?
> Best Wishes!
> QIU Nan
> 2010-03-24
>
>
>
>
> -------------------------------------------------------
> --
> Bruce Ravel ----------------------------------- bravel at bnl.gov
>
> National Institute of Standards and Technology
> Synchrotron Measurements Group, Beamlines X23A2, X24A, U7A
>
> Building 535A, Room M7
> Brookhaven National Laboratory
> Upton NY, 11973, USA
>
> My homepage: http://xafs.org/BruceRavel
> EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/
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