I definitely recommend combining multiple atoms of similar distances into the same path. That's what you end up with anyway if you use multiple paths, with a lot more potential problems in the software.
Sometimes it is beneficial to split a shell of of atoms into two, to capture some physical behavior (for example, 2 atoms at 3 Angstroms and 4 atoms at 3.3 Angstroms, instead of one very disordered shell of 6 atoms at 3.2 Angstroms). Depending on your data quality, I recommend building a fitting model with maybe 2-8 total "shells" of atoms at different distances. Mike > On Oct 26, 2017, at 12:52 PM, Yunyun Zhou <yyzhouz...@gmail.com> wrote: > > Hello All, > > I am having trouble fitting my sample with both Fe5C2 and Fe3O4 as standards. > Hopefully somebody could help me out and I really appreciate it. > > My iron sample was mainly iron carbide in the core and iron oxide on the > shell. Fe5C2 has a monoclinic structure and generated complicated FEFF paths. > Many of the paths have similar distances. I have found some paper reported > their results as follows, which apparently combined several paths together > and assume they have similar path length. My first question is does someone > know how they did it? It seems that combing similar paths makes fitting much > easier, but I am not sure whether this is a correct way to do the fitting. > > My second question is regarding fitting with the two combined models of Fe5C2 > and Fe3O4. I haven't fit with two models before. Is it just like what I did > in the attached Artemis file? Shall there be any restrictions between the two > models and do I have to fix some of the parameters? > > Thank you very much in advance for your help! > > Best, > > Yunyun Zhou > > Fe5C2 FEff paths: > <image.png> > > Literature reported results: > <image.png> > <artemis_CWV 130 spent_example.fpj> > _______________________________________________ > Ifeffit mailing list > Ifeffit@millenia.cars.aps.anl.gov > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
