[GSAS-II] Instrument parameters

[Toby, Brian H.]

Hi Huang,

    First of all Si is not a good standard to use for instrument parameters. It has no peaks at low angle. LaB6 is a better choice. If you do not have that, perhaps others seeing this can recommend something readily available with plenty of sharp peaks.

    GSAS-II has no limits on the number of phases that can be read, but there was a bug with reading that particular  CIF. In it the element types were specified as Ti0, Fe0 and O0 which GSAS-II could not process. I have repaired this bug in version #4887.

Brian

On Apr 18, 2021, at 6:04 PM, Huang Liu via GSAS-II <gsas-ii at aps.anl.gov<mailto:gsas-ii at aps.anl.gov>> wrote:

Hi,

This is Huang Liu from the University of Utah. I am trying to use GSAS 2 to do refinement on my data.
1. I try to get the instrument parameters according to the tutorial
 (https://subversion.xray.aps.anl.gov/pyGSAS/Tutorials/CWInstDemo/FindProfParamCW.htm).
But the U parameters that I get are always negative, and the Rwp is above 10. I am using the data generated byRigaku mini flex 600 by using SRM Si 640d as a standard sample for generating instrument profile parameters.   The attached file (Si-640d) is the original data.
Could you please help me generate the instrument profile?  Thank you very much.
2. I try to import Ti2Fe4O phase into the GSAS2, but I failed.
Since this is the third phase that I want to import. May I ask is there a phase quantities limit of import?
If not, is there anything wrong with my CIF file (I downloaded it from the COD website?
Attached is the Ti2Fe4O cif card downloaded from COD website.
I would be very grateful if you can help me. Looking forward to your reply.

Best regards,
Huang Liu
<Si-640d.ras><Ti4Fe2O.cif>_______________________________________________
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