[Ifeffit] Two absorbing atom sites

Richard Mayes rtmayes at gmail.com
Thu Nov 5 09:33:16 CST 2009


I have no experience with dopants, but I know it has been discussed on the
mail list.  A quick search of the mail list should turn up some valuable
information (Google helps with that, restrict the domain to
http://millenia.cars.aps.anl.gov/pipermail/ifeffit/ in Google's advanced

Also, I think this was also discussed in a tutorial or workshop listed on
www.xafs.org at one time.  You may want to look there as well.


On Tue, Nov 3, 2009 at 4:43 PM, Yun Luo <luoy1 at muohio.edu> wrote:

> Dear IFEFFIT List,
> I learned that IFEEFIT can model a single absorber in two different
> environment. Could anyone direct me to similar studies that have been done
> or related tutorials?
> Below are some thoughts and questions:
> For example, there is 2 wt% A in both M1 and M2 structural sites in crystal
> X as dopant.
> I first create 2 FEFF models in Artemis, one has absorbing atom A only in
> M1 site and the other one has A only in M2 site. In the fitting process, is
> it correct that I choose paths from both FEFF models and using different Eo
> and So^2 for M1 and M2 sites?
> And to model the site occupancy of A in each site, I can create a fraction
> parameter "a" (which means there are a*2 wt% A in M1 site and (1-a)*2 wt% A
> in M2 site). Is it correct to apply this fraction parameter only to So^2 to
> model the site occupancy of A in M1 and M2 site?
> I am worried this approach will use too many variables. Any suggestions on
> the constraints/restraints that I can use?
> Finally, is there anything else that I missed which needs to be considered
> to do the modeling for this case of two different absorbing atom sites?
> Any suggestion will be greatly appreciated! Thank you all in advance!
> Best regards!
> Yun
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