Regarding dopant additions in ATOMS
Hi everyone, I am having an issue trying to figure out a way to simulate the XANES environment using FEFF 8.4 for some catalyst we are working with. What I am trying to do is use different structures from a crystal database which are from the Rietveld Structure Refinement method from the XRD patterns. The issue I'm having is trying to account for vacancies, which when compiling the crystal structure in ATOMS I think I am allowed to have 9 dopants (from the ATOMS manual, however it is saying there is an error past five dopants, all of which are null, but that is irrelevant I guess) " *** Warning at line 13 You have exceeded the maximum number of dopants. ATOMS will ignore this and all further dopants.-" I'm wondering if there is a better way to account for site occupancies <1, or whether this is altogether a bad idea to try and simulate the XANES environment in the first place. ATOMS is a great program however I might be doing something wrong. I appreciate any insight anyone can give in this! Sincerely, Andrew Campos
Andrew, Feff only allows 8 kinds of atoms -- the absorber is number 0. Then you can have 7 other types of atoms in the calculation. As for your question about dopants, check out this mailing list post I wrote several years back: http://millenia.cars.aps.anl.gov/pipermail/ifeffit/2002-July/000092.html Question 14 at http://cars9.uchicago.edu/iffwiki/FAQ/FeffitModeling carries on the discussion. If, after reading those links and the material they point to, you still have specific questions -- ask away and we'll try to answer. Regards, B On Thursday 02 August 2007, Andrew Campos wrote:
Hi everyone,
I am having an issue trying to figure out a way to simulate the XANES environment using FEFF 8.4 for some catalyst we are working with. What I am trying to do is use different structures from a crystal database which are from the Rietveld Structure Refinement method from the XRD patterns. The issue I'm having is trying to account for vacancies, which when compiling the crystal structure in ATOMS I think I am allowed to have 9 dopants (from the ATOMS manual, however it is saying there is an error past five dopants, all of which are null, but that is irrelevant I guess)
" *** Warning at line 13
You have exceeded the maximum number of dopants.
ATOMS will ignore this and all further dopants.-"
I'm wondering if there is a better way to account for site occupancies <1, or whether this is altogether a bad idea to try and simulate the XANES environment in the first place. ATOMS is a great program however I might be doing something wrong. I appreciate any insight anyone can give in this!
Sincerely, Andrew Campos
-- 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/exafs/
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Andrew Campos -
Bruce Ravel