<html xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=Windows-1252">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
.MsoChpDefault
{mso-style-type:export-only;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style>
</head>
<body lang="EN-US" link="blue" vlink="#954F72" style="word-wrap:break-word">
<div class="WordSection1">
<p class="MsoNormal">Nithya,</p>
<p class="MsoNormal">�Chi^2� is the sum of W*(Yo-Yc)^2; this is the thing that is minimized by the least squares and is a large number. It is roughly equal to the number of observations in a well refined system. Many folks mistakenly call chi^2/(Nobs-Nvar)
as �chi^2�; that is really �reduced chi^2�. GOF = sqrt(reduced chi^2).</p>
<p class="MsoNormal">Best,</p>
<p class="MsoNormal">Bob</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Sent from <a href="https://go.microsoft.com/fwlink/?LinkId=550986">
Mail</a> for Windows 10</p>
<p class="MsoNormal"><o:p> </o:p></p>
<div style="mso-element:para-border-div;border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal" style="border:none;padding:0in"><b>From: </b><a href="mailto:nithya@igcar.gov.in">nithya@igcar.gov.in</a><br>
<b>Sent: </b>Wednesday, April 21, 2021 4:30 AM<br>
<b>To: </b><a href="mailto:vondreele@anl.gov">Von Dreele, Robert B.</a><br>
<b>Subject: </b>Re: [GSAS-II] Clarification on using GSAS 2</p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Dear Bob,<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black"> <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black"> Thanks for a prompt reply. I am still confused why the value of Chi2 is so high? Is this parameter equivalent to the one (of the R-factors) we get in the refinement performed using GSAS
EXPGUI? Alos I would like to find out what all the R parameters that should be given for publishing in journals?<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black"> <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black"> Right now I am using GSAS-II revision 4408 (SVN version 4408). How can get updates of GSAS II in my computer?
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black"> <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">with regards,<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Nithya<o:p></o:p></span></p>
</div>
<div>
<div>
<div>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black"> <o:p></o:p></span></p>
</div>
<div>
<div>
<p class="MsoNormal" style="background:whitesmoke"><b><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black"> Von Dreele, Robert B.
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal" style="background:whitesmoke"><b><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black">Sent:</span></b><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black"> Tuesday, April 20, 2021 6:36 PM<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal" style="background:whitesmoke"><b><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black">To:</span></b><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black"> nithya@igcar.gov.in ; Toby, Brian H.
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal" style="background:whitesmoke"><b><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black">Subject:</span></b><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black"> RE: [GSAS-II] Clarification on using
GSAS 2<o:p></o:p></span></p>
</div>
</div>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black"> <o:p></o:p></span></p>
</div>
</div>
<div>
<p class="MsoNormal"><span style="color:black">Dear Nithya,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:black">Given that your GOF is close to 1 (=1.53), you won�t do any better. If the difference curve reveals no remaining peak shape, position, intensity issues, then you are done. The high Rwp is probably because you didn�t
count long enough to get a clean background (that�s where a good part of Rwp may come from).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:black">The Ru+5 & Co+4 oxidation states exist as an electron counting requirement; the actual electron distribution is much closer to neutral atoms so one ought to use those for all atoms. In any event, the form factors
for any element & its various valence states are essentially identical for most of the diffraction pattern above say 10deg 2-theta for Cu Ka radiation. My advice is to use zero valent atoms for all atoms irrespective of the apparent chemical valence.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:black">Best,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:black">Bob<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:black"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:black">Sent from <a href="https://go.microsoft.com/fwlink/?LinkId=550986">
Mail</a> for Windows 10<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:black"> <o:p></o:p></span></p>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="color:black">From: </span></b><span style="color:black">Nithya via GSAS-II<br>
<b>Sent: </b>Tuesday, April 20, 2021 3:42 AM<br>
<b>To: </b>gsas-ii@aps.anl.gov<br>
<b>Cc: </b>Nithya R.<br>
<b>Subject: </b>[GSAS-II] Clarification on using GSAS 2<o:p></o:p></span></p>
</div>
<p class="MsoNormal"><span style="color:black"> <o:p></o:p></span></p>
<div>
<div>
<div>
<div>
<div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Hi,<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black"> <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black"> This is Dr. Nithya Ravindran from India. I am using GSAS II to extract structural information of double perovskites and I have a couple of doubts to be clarified. They are listed below:<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black"> <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">1. After a few iterations of refinement, a stable wR on 1399 observations 15.572% is obtained. Not able to refine further to reduce this value. Visual inspection of the plot of experimental and
computed powder diffraction profile agrees well. Can this value be considered acceptable to rely on structural parameters? We get Chi2 value very high (as high as 3213.91) and GOF 1.53; and RF AND RF2 4.958% AND 9.369% respectively on 12 reflections. If
not, what should be the minimum value of wR for a good fit?<o:p></o:p></span></p>
</div>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">2. in two of the ruthenium and cobalt based double perovskites, Ru and Co exist in +5 and +4 oxidation states respectively. Unable to select these ions as they are not included in the program.
Please clarify.<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black"> <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Thank you,<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">With warm regards,<o:p></o:p></span></p>
</div>
</div>
</div>
</div>
</div>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Nithya<o:p></o:p></span></p>
</div>
</div>
</div>
<p class="MsoNormal"><span style="color:black"> <o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</body>
</html>