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<div class="">I have not thought about if your constraint is a good idea, but I want to confirm that this type of constraint is not allowed within the current GUI. </div>
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<div class="">The underlying constraint mechanism within GSAS-II would allow it to be included if input, but I am not sure how to write an interface that allows input and editing of completely general constraints. </div>
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<div class="">Brian</div>
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<blockquote type="cite" class="">
<div class="">On Oct 18, 2016, at 8:10 AM, Ivo Alxneit <<a href="mailto:ivo.alxneit@psi.ch" class="">ivo.alxneit@psi.ch</a>> wrote:</div>
<br class="Apple-interchange-newline">
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<div class="">Dear all<br class="">
<br class="">
I have a series of X-ray powder diffractograms that show the segregation<br class="">
of platinum from Pt4+ doped ceria. I would like to analyze the<br class="">
segregation kinetics from these data.<br class="">
<br class="">
I fit the Histogram Scale Factor and define a constrain that all phase<br class="">
fractions add up to 1.0. For consistency I would like to set up a<br class="">
constrain of the form<br class="">
<br class="">
<span class="Apple-tab-span" style="white-space:pre"></span>0:0:Scale * 0::Afrac:3 + 1:0:Scale<br class="">
<br class="">
fraction_doped_ceria * Pt4+ occupancy plus fraction_segregated_platinum<br class="">
<br class="">
i.e. a constrain that makes the amount of platinum in the system<br class="">
constant (under the assumption that all platinum is 'visible' i.e. no<br class="">
X-ray amorphous Pt clusters are present).<br class="">
<br class="">
At present (Rev 2493) this does not seem to be possible and I try to<br class="">
manually set the correct Pt4+ occupancy. This is rather tedious<br class="">
iteration process. Could this be implemented in GSASII or is my analysis<br class="">
faulted?<br class="">
<br class="">
Thanks for any suggestions<br class="">
-- <br class="">
Dr. Ivo Alxneit<br class="">
Catalysis for Energy Group<br class="">
Bioenergy and Catalysis Laboratory phone: +41 56 310 4092<br class="">
Paul Scherrer Institute fax: +41 56 310 2688<br class="">
CH-5232 Villigen gnupg key: 0x515E30C7<br class="">
Switzerland<br class="">
<a href="https://www.psi.ch/ceg/catalysis-for-energy-group/" class="">https://www.psi.ch/ceg/catalysis-for-energy-group/</a><br class="">
<br class="">
_______________________________________________<br class="">
GSAS-II mailing list<br class="">
GSAS-II@mailman.aps.anl.gov<br class="">
https://mailman.aps.anl.gov/mailman/listinfo/gsas-ii</div>
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<div style="margin: 0px;" class=""><font class="Apple-style-span" face="Courier">Brian H. Toby, Ph.D. office: 630-252-5488</font></div>
<div style="margin: 0px;" class=""><span style="font-family: Courier;" class="">Advanced Photon Source </span><font class="Apple-style-span" face="Courier">Chief Computational Scientist</font></div>
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