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 -- Bruce Ravel ---------------------------------------------- bravel@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 My homepage: http://cars9.uchicago.edu/~ravel EXAFS software: http://cars9.uchicago.edu/~ravel/software/