> 1. Are the phase fractions in the GSAS output expressed as weight or molar
> fractions?
They are given as the ratios of the number of unit cells, but in the LST
file als the fraction by weight is given.
> 2. I have to introduce a constraint on the phase fractions:
> f(phase1)+f(phase2)=1. I have one histogram.
> I think it should have the form: "1,1 1.0 2,1 -1.0" Is it correct?
You can do it a lot easier! Just refine only one of the phase fractions,
or both and switch of the histogram scale factor. You have two phases, so
two degrees of freedom. You can do it of course by using this constraint.
> "ISAM record with KEY="CRS1 SPNFLP" has problems Stop Program Terminated"
> Am I missing some important parameter that needs to be set or just my
> model is wrong?
No, it is just a standard problem, go to
least squares --> atoms --> magnetic information --> spin flip --> and
that is enough. It just means that one line in the EXP file is missing and
you have to create it. By the way I normally use a second phase for which
I only calculate the magnetic contributions, and use space group P1.
Doing so, I found it easier to manipulate the different magnetic
structures.
Good luck
Jaap
Jaap Vente
Cinvestav-IPN Unidad Merida
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