[GSAS-II] Clarification Request (MuStrain, Size)

[Toby, Brian H.]

Hi Audrey,

   I have not looked at the code, but GSAS-II uses microstrain and size parameters in only one way. They are called "HAP" because there is a set for each phase and for each histogram. Thus, if you are doing a simulation of one powder pattern for a two-phase mixture, each phase could have different size and mustrain values.

   Having said that, there can be a number of ways in GSASIIscriptable to set those values. Most likely I set up something general and clumsy initially and then wrote a new and improved and more specific routine later, but left the old one because it could be used for more purposes or so that I would not break old scripts. While not recommended, it is even possible to find the entries in the Phase.data object and change them directly.

When in doubt, you can create or modify the .gpx file in a script, save it and look at the values using the GUI. Or, to see what is changing in the underlying data structures, change a value in the GUI, save it and then look at the various dicts from a script.

Does this answer your question?

Brian
________________________________
From: GSAS-II <gsas-ii-bounces at aps.anl.gov> on behalf of Audrey Mayrat via GSAS-II <gsas-ii at aps.anl.gov>
Sent: Monday, March 1, 2021 2:58 AM
To: gsas-ii at aps.anl.gov <gsas-ii at aps.anl.gov>
Subject: [GSAS-II] Clarification Request (MuStrain, Size)

Good Morning,

I am using the python interface to do continus simulation. Those simulations will be used to train neural networks for the phase detection and quantification.

While doing it, I discovered that there was 2 ways to play with both the Mustrain et the Size parameters (using set H-A-P set parameter and set profile parameter), that to me seems equivalent, beside the profile settings (Gaussian or Lauretzian).

I would like to know what is the difference between both, when used for the simulation of XRD patterns, and which one in my cases would be the most suitable ?

If any one as the answer or hypothesis about it, feel free to answer.

Best Regards

A. M.
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