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<div>I am forwarding this to get Bob's reply into the archives. </div>
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<div>I'd like to also add that the PDF routine in GSAS-II needs some more validation. It simplifies all the semi-rigorous corrections usually applied for x-ray PDFs into a single <i>ad hoc</i> correction value that can be varied with a slider to find the optimal.
We would be interested in feedback on how this performs. </div>
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<div>Begin forwarded message:</div>
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<blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; ">Shoaib,<br>
Although Brian's remark is true - a PDF with CuKa radiations is quite poor - one can generate it quite simply in GSAS-II. The steps are:<br>
1) Select 'Make new PDFs' from the main Calculate menu - this will make a new entry 'PDF' in the data tree.<br>
2) Under 'PDF' select 'PDF Controls' and Add element for each element in your sample<br>
3) For each element change the number to match the composition (could be # per cell) - a PDF will be computed automatically<br>
4) Adjust the formula volume as needed and set other parameters as needed - each time the PDF will be updated.<br>
5) Look at G(r) & F(Q); G(r) should have minimal features at G(0) & F(Q) should taper smoothly to zero at large Q adjust slider to best fit.<br>
GSAS-II has no PDF modeling tools & the PDF generator is still under development, thus no tutorial for it.<br>
Best,<br>
Bob Von Dreele<br>
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