source: trunk/tutorial1/nickel7.html @ 930

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1<html>
2<head>
3   <title>EXPGUI Tutorial #7</title>
4</head>
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15<?
16   include("/var/www/include/navigation.inc");
17   include("/var/www/include/utility.inc");
18?>
19<blockquote>
20
21<CENTER>
22<H1>GSAS Nickel example using EXPGUI (part 7)</H1>
23</CENTER>
24<H1>
257. Setup for Least-Squares Refinement
26</H1>
27
28Before the model can be refined to better fit the data, the
29structure must be entered. When starting with a new model
30it is a good idea to refine the scale factors for each histogram
31and the background terms before refining any structural parameters.
32So EXPGUI will be used to check which parameters are set to be refined.
33
34<img src="addatom1.gif" align=left>
35Select a phase by pressing the "1" button in the upper left.
36Then add an atom to the model by pressing the "Add New Atom" button
37in the lower right side of the Phase pane
38<a href="nickel2.html#phasepane">(shown in part 2)</a>.
39After entering the atom type, the
40coordinates added, and changing the Uiso value to match the example,
41press "Add" to add the atom to the .EXP file.
42<BR clear=left><P>
43<img src="addatom2.gif" align=left>
44A box then appears, as shown to the left, to show the results when the atom is read into EXPTOOL.
45<BR clear=left><P>
46<img src="addatom3.gif">
47<BR clear=left>
48Note that the atom now appears on the phase page. Also note that the cell
49will not be refined, since the "Refine Cell" checkbutton in the upper right
50is not checked. Nor are any atomic parameters being refined, since X V and F
51do not appear in the ref./damp column.
52<BR clear=left>
53<P>
54<img src="bkg1.gif">
55<BR clear=left>
56We then check each histogram from the Histogram pane, and see that
57the background function has been set to type 4, with 4 terms, as recommended
58in the tutorial, and that no diffractometer constants will be refined
59(above and below).
60<BR clear=left>
61<img src="bkg2.gif">
62<BR clear=left>
63<P>
64<img src="scale1.gif">
65<BR clear=left>
66We can quickly confirm that the scale factors for the two
67histograms will be refined on the Scaling pane
68(above and below).
69<BR clear=left>
70<img src="scale2.gif">
71<BR clear=left>
72<P>
73<img src="prof1.gif">
74<BR clear=left>
75Finally we check that no profile terms are being refined on the Profile
76panes.
77(above and below).
78<BR clear=left>
79<img src="prof2.gif">
80<BR clear=left>
81
82<P><BR>(.EXP Snapshot:
83<A HREF="ftp://ftp.ncnr.nist.gov/pub/cryst/gsas/tutorials/nickel7.exp">
84nickel7.exp
85</A>)
86
87
88<BR clear=left><HR>
89Previous step: <A HREF="nickel6.html">
90Plot data using POWPLOT or LIVEPLOT</A>
91<BR>
92Next step: <A HREF="nickel8.html">
93Run GENLES</A>
94
95<HR>
96</blockquote>
97<P><font size=-1><A HREF="MAILTO:crystal@NIST.gov?subject=WWW page <?=$PHP_SELF?>">Comments, corrections or questions: crystal@NIST.gov</A></font><BR>
98<font size=-1><? lastmod(); ?> </font>
99<BR>$Revision: 930 $ $Date: 2009-12-04 23:14:35 +0000 (Fri, 04 Dec 2009) $
100</body>
101</html>
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