[Ifeffit] Feff for > 175 atoms

Bruce Ravel bravel at anl.gov
Mon Aug 20 08:15:14 CDT 2007

On Monday 20 August 2007, s440697 at stud.uni-goettingen.de wrote:
> Hello,
> i tried to run feff with a atomcluster of 249 atoms (under linux) and got
> this message:
> You specified a cluster of 249 atoms for the FMS calculation.
> This exceeds the hard wired limit of 175 atoms.
> The cluster size was reset to 175 and the calculation will continue.
> Then i made a feff-run with feff84_300.exe (under windows) with the same
> 249-atomcluster. This worked fine. But is there a linux-version for 300
> atoms? Or is there a way to make a feff-run under linux with such big
> cluster?
> I would be very thankful for an answer :-)


This is not a version problem, per se.  The issue is how the various
constants are set when Feff is compiled.  When you unpack the source
code for feff, you will see a whole slew of directories.  One of them
is called "HEADERS/".  In that directory is a file called "dim.h".
Near the top of that file, you will find a constant called "nclusx".
In the source tarball, this parameter is set to 175, but you can
change it and recompile.

Once you change that value to 300 (or whatever) and recompile Feff,
you should be able to run your problem on your linux machine.  I
suspect (but do not know for sure) that the only difference between
the windows feff84_300.exe and the normal feff84.exe is the size of
the nclusx parameter.


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

 Molecular Environmental Science Group, Building 203, Room E-165
 MRCAT, Sector 10, Advanced Photon Source, Building 433, Room B007

 Argonne National Laboratory         phone and voice mail: (1) 630 252 5033
 Argonne IL 60439, USA                                fax: (1) 630 252 9793

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