[Ifeffit] odd feff6 behavior

Anatoly Frenkel frenkel at bnl.gov
Fri Jun 10 16:05:50 CDT 2005


[Ifeffit] odd feff6 behaviorBruce,

I checked that the same problem existed for the original FEFF601.f fortran
file in UNIX. I looked for the string "np > np1x" and found that the code
stops when this condition is true. np1x is a fixed parameter defined in the
code as parameter (np1x = 12000). When np (the paths counter) becomes 12001
(it is incremented in the code as the paths are counted), the code stops.
Apparently, for this structure it happens for rmax exceeds 6.6 . When rmax =
6.6, the number of paths is less than 12000, and the code does not stop. I
do not know why 12000 was chosen as a threshold... we can ask
Alex.Therefore, if you have access to the feff6 source that is used in
IFEFFIT (I assume you do), you can increase the np1x and recompile.
Regards,

Anatoly

******************
Anatoly Frenkel, Ph.D.
Associate Professor
Physics Department
Yeshiva University
245 Lexington Avenue
New York, NY 10016

(YU)  212-340-7827
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  -----Original Message-----
  From: ifeffit-bounces at millenia.cars.aps.anl.gov
[mailto:ifeffit-bounces at millenia.cars.aps.anl.gov]On Behalf Of Bruce Ravel
  Sent: Friday, June 10, 2005 3:43 PM
  To: XAFS Analysis using Ifeffit
  Subject: [Ifeffit] odd feff6 behavior





  Hi,

  Here's a feff6 curiosity.  Take this atoms.inp file:

    title = TiN
    space = 225
    a =       4.24173       b =       4.24173       c =       4.24173
    core =  Ti      edge =  K       rmax =    7.0
    atoms
    ! elem   x          y          z
      Ti    0.00000    0.00000    0.00000
      N     0.50000    0.50000    0.50000



  Run atoms, then run feff6l (the one that comes with Ifeffit, it's the only
  version I've tried this with).  Feff ends with this error message:
      Eliminating path degeneracies...
         Plane wave chi amplitude filter   2.50%
        np, np1x=    12001   12000
      Fatal Error: at PATHSD: np > np1x

  This message comes from pathsd.f, but I don't understand either the
message or
  the part of the code it comes from.  Does anyone else have a hint as to
the
  problem?

  One more datum.  If you reduce rmax to 6.7 in the atoms.inp file, the
problme
  persists.  If you make rmax 6.6, feff6l is happy.

  Thanks,
  B



  --
   Bruce Ravel  ----------------------------------- bravel at anl.gov  -or-

ravel at phys.washington.edu
   Environmental Research Division, Building 203, Room E-165
   Argonne National Laboratory                        phone: (1) 630 252
5033
   Argonne IL 60439, USA                                fax: (1) 630 252
9793

   My homepage:    http://feff.phys.washington.edu/~ravel
   EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/

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