Dominik's answer sounds right to me. See question 15 at http://cars9.uchicago.edu/ifeffit/FAQ/FeffitModeling
B On Wednesday, August 18, 2010 02:36:03 am Dominik Samuelis wrote: > Dear Kleper, > > even though I haven't tested it in detail, I'm sure the errors come from > the fact that ATOMS cannot handle site occupancies other than unity. If > you have a look in the cif file, you can see that both W (0.23) and Ti > (0.54) have a fractional occupancy: > > loop_ > _atom_site_label > _atom_site_type_symbol > _atom_site_symmetry_multiplicity > _atom_site_Wyckoff_symbol > _atom_site_fract_x > _atom_site_fract_y > _atom_site_fract_z > _atom_site_occupancy > _atom_site_attached_hydrogens > _atom_site_calc_flag > W1 W4+ 4 e 0. 0. 0.0564(2) 0.23 0 d > Ti1 Ti4+ 2 a 0. 0. 0. 0.54 0 d > O1 O2- 4 f 0.3007(6) 0.3007(6) 0. 1. 0 d > > To get it working, you need to use the prototypical structure (e.g. TiO2) > without mixed sites as ATOMS input. In the feff.inp file, you can then > change 46 out of 100 Ti atoms to W (5 out of 10 should be ok as well for a > smaller cluster). Don't forget to add the appropriate POTENTIALS line for > W to the feff.inp. The small shift of the W atoms away from the Ti > positions then could be handled by some additional delR parameter for the > W paths during fitting. > > All the best, > Dominik > > Am 17.08.2010 um 15:27 schrieb Kleper Rocha: > > Please, > > > > Could someone help me with the cif file attached, get from the > > www.crystallographic.net shearch with the terms Ti, W, O. When I try to > > run the Feff the following message appears. > > > > "Feff 6L.02 > > > > WARNING: TWO ATOMS VERY CLOSE TOGETHER. CHECK INPUT. > > > > atoms 1 2 > > > > 1 0.00000 0.00000 0.00000 > > 2 0.00000 0.00000 -0.16378 > > > > Run continues... > > WARNING: TWO ATOMS VERY CLOSE TOGETHER. CHECK INPUT. > > > > atoms 1 3 > > > > 1 0.00000 0.00000 0.00000 > > 3 0.00000 0.00000 -0.32756 > > > > Run continues... > > WARNING: TWO ATOMS VERY CLOSE TOGETHER. CHECK INPUT. > > > > atoms 2 3 > > > > 2 0.00000 0.00000 -0.16378 > > 3 0.00000 0.00000 -0.32756 > > > > Run continues... > > WARNING: TWO ATOMS VERY CLOSE TOGETHER. CHECK INPUT. > > > > atoms 10 11 > > > > 10 0.00000 0.00000 2.57634 > > 11 0.00000 0.00000 2.74012 > > > > Run continues... > > WARNING: TWO ATOMS VERY CLOSE TOGETHER. CHECK INPUT. > > > > atoms 10 12 > > > > 10 0.00000 0.00000 2.57634 > > 12 0.00000 0.00000 2.90390 > > > > Run continues... > > WARNING: TWO ATOMS VERY CLOSE TOGETHER. CHECK INPUT. > > > > atoms 11 12 > > > > 11 0.00000 0.00000 2.74012 > > 12 0.00000 0.00000 2.90390 > > > > Run continues... > > WARNING: TWO ATOMS VERY CLOSE TOGETHER. CHECK INPUT. > > > > atoms 13 14 > > > > 13 0.00000 0.00000 -2.90390 > > 14 0.00000 0.00000 -3.06768 > > > > Run continues... > > > > Titanium tungsten oxide (0.54/0.46/2) > > Ti.54 W.46 O2 > > O2 Ti0.54 W0.46 > > Peters, E. > > Ueber ein niedervalentes Titan-Wolframoxid: Ti0,54 W0,46 O2 > > Calculating potentials and phases... > > > > free atom potential and density for atom type 0 > > free atom potential and density for atom type 1 > > free atom potential and density for atom type 2 > > free atom potential and density for atom type 3 > > overlapped potential and density for unique potential 0 > > overlapped potential and density for unique potential 1 > > overlapped potential and density for unique potential 2 > > overlapped potential and density for unique potential 3 > > muffin tin radii and interstitial parameters > > > > This warning indicates a problem in the Atoms list. For some > > reason you have atoms that are separated by than 0.93 Angstroms > > (or 1.75 Rydberg). > > > > This may be due to the presence of hydrogen atoms in your feff.inp > > file, in which case this is an innocuous warning and may be ignored. > > > > However, this may indicate a problem constructing the Atoms > > list. The most common cause of this problem is a mistake in the > > crystallographic data used on the Atoms page. You may have > > incorrect values for lattice constants or angles or incorrect > > values for site coordinates. You may need a shift vector to move > > the lattice into its standard setting. > > > > Please be aware that Atoms works with 5 digits of precision. > > Thus, if you have a site with a coordinate of 1/3, you should use > > either "1/3" or "0.33333" on the Atoms page. Using insufficient > > precision, say "0.333" is a common cause of this error message. > > > > Artemis has continued on the possibility that the warning is > > caused by hydrogen atoms, but be warned that the feff.inp may > > require your attention." > > > > Thanks in advance. > > > > > > > > Kleper de Oliveira Rocha > > > > <O2 Ti0.54 W0.46.cif>_______________________________________________ > > Ifeffit mailing list > > [email protected] > > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit -- Bruce Ravel ------------------------------------ [email protected] National Institute of Standards and Technology Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2 Building 535A Upton NY, 11973 My homepage: http://xafs.org/BruceRavel EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/ _______________________________________________ Ifeffit mailing list [email protected] http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
