Dear all, I am new to GSAS II and have no experience with old-GSAS, so forgive me for the basic level of the questions.
I don't fully understand the meaning of the parameters describing the instrumental profile. · What is Z? I could not find it in the old-GSAS manual. · How can I judge if the U V W X Y Z are reasonable? (in case I don't have a reference profile from a standard) And how should a well behaved peak width plot look like? · I read that U W X Y are constrained to be >= 0, while V should be <= 0. However I have a not so badly-fitted plot where U refined to very negative, V to very positive, W is small and negative, X is positive and Y negative. So (i) those parameters have no constraint by default!Why not? Can I do it with equations?; (ii) even from my naïve understanding it looks like a nonsense. Most likely it is because I have broad peaks and the interplay between strain/size/etc and instrumental parameters converged to this artificial mess. Is it possible to deconvolute the instrument contribution from the sample contribution, in absence of a standard? · SH/L is one unique parameter as opposed to 2 separate parameters in old-GSAS, what is its meaning now, the units and/or reasonable range? If you can help with even partial answers or point out useful sources of information, I will be grateful! Kind regards, Arianna ,_,.-'´¨´'-.,_,.-'´¨´'-.,_,.-'´¨´'-.,_,,.-'´¨´'-.,_,.-'´¨´'-.,_, Arianna Lanza, PhD Center for Nanotechnology Innovation@NEST Istituto Italiano di Tecnologia Piazza San Silvestro, 12, 56127, PISA, Italy
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