[Ifeffit] iPot Exceeded

[Bruce Ravel]

On Wednesday 01 September 2004 10:45 am, Barton, David (DG) wrote:
> Thanks to Bruce for releasing the new versions.  He has been extremely
> responsive to dealing with most of my bug reports and suggestions for
> change.  The implementation of reading CIF files directly into Artemis and
> Atoms makes going from crystal structures in a database to simulated EXAFS
> patterns almost trivial.  O.K. enough padding Bruce's ego...now for a
> question.

It's quite all right.  You don't need to stop... ;-)

I'm glad the CIF thing is making you happy.

> Artemis 0.7.010, with FEFF6L on WinXP machine:
>
> What is the best way to deal with a crystalline compound in Artemis/FEFF
> that has 9 unique elements?

   <snip>

>  ipot   Z  element
>         0   79   Au
>         1    7   N
>         2    6   C
>         3    5   B
>         4    9   F
>         5    8   O
>         6    1   H
>         7   79   Au
>         8   15   P

My memory is that it is non-trivial to increase the number of unique
potentials in Feff, but perhaps that's not the case.  Perhaps it would
be easy to recompile Feff to allow for more potantials.

Removing the hydrogens is a good solution.

Another thing that would probably work well would be to treat atoms
whose Z numbers differ by one as the same.  For instance, if there are
only a few B atoms in your material, treat them all as carbon.  In
Feff6, which does not do the self-consistency loop, this should be a
reasonable approximation.  (It even may be in Feff8, for all I know.)

> It would be helpful if the Atoms input page would allow the user to
> sort the atomic positions by element and then select a range of
> these atomic positions and delete them all.

I will be revamping the Atoms page in the development version of
Artemis.  The new format will make sorting easy.  I'll put this
suggestion on the list of things to do.

Thanks for all your great feedback, Dave.  You are making quite a
positive impact on my software.

B

-- 
 Bruce Ravel  ----------------------------------- ravel at phys.washington.edu
 Code 6134, Building 3, Room 405
 Naval Research Laboratory                          phone: (1) 202 767 2268
 Washington DC 20375, USA                             fax: (1) 202 767 4642

 NRL Synchrotron Radiation Consortium (NRL-SRC)
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 National Synchrotron Light Source
 Brookhaven National Laboratory, Upton, NY 11973

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