source: tutorials/tutorial1/nickel7.html @ 1148

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1<html>
2<head>
3   <title>EXPGUI Tutorial #7</title>
4</head>
5
6<style>
7A:link {text-decoration:none}
8A:vlink {text-decoration:none}
9</style>
10
11<BODY BGCOLOR="#FFFFFF"
12      topmargin="0" leftmargin="0" marginwidth="0" marginheight="0" 
13      text="#000000" link="#0033ff" vlink="#0033ff" alink="#0033ff">
14
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, one must
29decide on the order of parameters to be optimized.
30When starting with a new model
31it is a good idea to refine the scale factors for each histogram
32and the background terms before refining any structural parameters.
33So below EXPGUI will be used to check which parameters are set to be refined.
34
35<img src="bkg1.gif">
36<BR clear=left>
37We then check each histogram from the Histogram pane, and see that
38the background function has been set to type 4, with 4 terms, as recommended
39in the tutorial, and that no diffractometer constants will be refined
40(above and below).
41<BR clear=left>
42<img src="bkg2.gif">
43<BR clear=left>
44<P>
45<img src="scale1.gif">
46<BR clear=left>
47We can quickly confirm that the scale factors for the two
48histograms will be refined on the Scaling pane
49(above and below).
50<BR clear=left>
51<img src="scale2.gif">
52<BR clear=left>
53<P>
54<img src="prof1.gif">
55<BR clear=left>
56Finally we check that no profile terms are being refined on the Profile
57panes.
58(above and below).
59<BR clear=left>
60<img src="prof2.gif">
61<BR clear=left>
62
63<P><BR>(.EXP Snapshot:
64<A HREF="ftp://ftp.ncnr.nist.gov/pub/cryst/gsas/tutorials/nickel7.exp">
65nickel7.exp
66</A>)
67
68
69<BR clear=left><HR>
70Previous step: <A HREF="nickel6.html">
71Plot data using POWPLOT or LIVEPLOT</A>
72<BR>
73Next step: <A HREF="nickel8.html">
74Run GENLES</A>
75
76<HR>
77</blockquote>
78</body>
79</html>
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