[GSAS-II] Refinement error "Invalid Metric Tensor"

[Sorub]

Dear Angshuman,
I had the same problem after installing the new GSAS II software; the old
version did not show this issue.
It looks like they removed the option "the sum of phase fractions to one"
in the new version. This problem will come if the histogram scale factor in
the sample parameter is 1.
If we allow the scale factor to vary by assigning values other than one, I
didn't find any issue.
Hopefully, someone will provide a correct solution to tackle this issue
Thanks
Sorb Yesudhas
Iowa State University

On Fri, Aug 12, 2022 at 12:48 AM Angshuman Gupta via GSAS-II <
gsas-ii at aps.anl.gov> wrote:

> Hello,
> I was trying to evaluate the phase fraction from a mixture of multiple
> phases using X-ray diffraction, collected using Cu Kalpha radiation. I went
> through the GSAS II tutorial video on how to perform Rietveld refinement
> for multiple phases at
> https://subversion.xray.aps.anl.gov/pyGSAS/Tutorials/SeqRefine/SequentialTutorial.htm
>
> Started the refinement by setting a constraint which fixes the sum of
> phase fractions to be one. I am getting a refinement error stating "Invalid
> metric tensor" when I was trying to refine unit cell parameters and phase
> fraction together.
> I will be thankful and appreciate any lead on how to tackle the error.
> Thank you
> Angshuman Gupta
> Indian Institute of Technology Bombay, India
>
> [image: image.png]
>
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