[Ifeffit] The most important fitting parameters

Bridget Ingham b.ingham at irl.cri.nz
Wed Jun 21 09:15:06 CDT 2006

Hi Bruce and Shelly, thanks for your replies.

The problem I am encountering is that we know virtually nothing about the
crystallography, only the elements that are present. We expect the structure
to be quite different to CuWO4, even though this is the stoichiometry

Addressing some of your questions/comments:


1) I will try this. In other systems I've tried the second oxygen shells
don't contribute significantly, so maybe they are unnecessary and only
adding to the uncertainty in the other shells.

2) & 3) As mentioned above, we don't even know this about the structure. But
it is worth me having a go at restricting the delr's to relate to CuWO4. I
am loathe to do the same with the amplitudes however, as I expect the
co-ordination numbers to be completely different.

4) Yes, I ran a CuWO4 standard at the same time. It looks completely
different ;)

5) & 6) Thanks for these tips!


I have kept E0 the same for all shells, hence 13 parameters (4 shells x amp,
delr, ss; plus E0). Sorry for not making that clear enough.
The data stops at 9 Ang-1 because there seems to be some Zn edge impurity :(

I will play around with the constraints a bit more (starting with the CuWO4
standard) and let you know how I get on. Thanks again for your help!


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