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Dear Gerard, If
I don’t misunderstand it’s function, Powpref setups a file for the refinement where the initial positions
and shapes of the peaks are written (together with other info) and the
intensities are zeroed. This implies that you should run Powpref
each time you modify (by hand) one parameter affecting them. For example, you
don’t need to run Powpref if you switch on or
off any refinement label, provided that you have not modified it’s value or the function that handles it before the
run. You
should always run powpref if you change profile
parameters, zero shift, cell parameters, background, among others, but you have
no need to do it if you change atomic positions or thermal parameters. However sometimes
it’s good to run it from time to time in order to have a “mark”
in the history, if you need to go back to a previous step. You
should take great care with powpref if you are
performing a Le Bail fit, because all the intensities are zeroed so you are
exactly back at the first step of the procedure after each powpref.
Follow Brian Toby’s suggestions on EXPGUI if you need more. http://www.ncnr.nist.gov/programs/crystallography/software/expgui/expgui.html Good
luck Leopoldo Dr. Leopoldo Suescun -----Mensaje original----- Dear
everybody, I am
just getting started in the Rietveld refinement method with GSAS, whenever i
run the command "Genles", which is an iterative algorithm to find the
minima in your variables set, i don't know wether I have to run before
"powpref" or not. GSAS gives you sometimes online hints about when
run it after changing a flag, but not always. Could
anybody help me in this issue? Thanks
indeed -- -- |
- Powpref Gerard, Garcia S
- Leopoldo Suescun
