[Ifeffit] Generating Atom lists using Artemis

[Bruce Ravel]

On Saturday 06 January 2007 10:53, Kelly, Shelly D. wrote:
> Hello Artemis users,
>
> I found an interesting feature in Artemis when generating a list of atoms
> from the attached cif file worth sharing on the list.  In the attached cif
> file for Pd2Si the position of the Si2 atoms are at x,y,z = 0.3333, 0.6667,
> 0 with a space group of p -6 2 m. Using this cif file and choosing either
> Pd1 or Pd2 as the core atom results in errors in the atom list.  For
> example for the Pd2 site there are 4 Si neighbors with the 1st and 3rd and
> the 2nd and 4th on top of each other.  If you edit the atomic positions so
> that the Si2 atoms are correct to an additional digit x,y,z = 0.33333,
> 0.66667,0 then the atom list is fixed with only two Pd2-Si neighbors at
> each of the unique positions.  The interesting feature is that the
> coordinates on the atoms page need to be correct to the 5 decimal place.


This has been discussed many, many times on the mailing list and is
explained in question 3 at
   http://cars9.uchicago.edu/iffwiki/FAQ/RunningFeff 

The version of Feff that ships with Ifeffit (and, I believe, all
others) uses 5 significant figures in the path finder.  Since Atoms
main purpose is to interact with Feff, it interprets the 5 digit thing
quite strictly.

B



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