source: trunk/tutorial2/garnet4.html @ 596

Last change on this file since 596 was 596, checked in by toby, 11 years ago

# on 2002/04/12 21:34:08, toby did:
remove id info; update format

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  • Property rcs:date set to 2002/04/12 21:34:08
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1<html>
2<head>
3   <title>EXPGUI Tutorial #4</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>EXPGUI Tutorial: Garnet (part 4)</H1>
23</CENTER>
24<H1>
254. Run POWPREF and GENLES
26</H1>
27<H3>POWPREF</H3>
28<img src="powpref2.gif" align=left>
29Before a least-squares refinement can be run, the POWPREF program
30must be run. This program assigns the reflections that are associated with
31each data point in each histogram. For this reason, POWPREF should
32be rerun if the lattice constants change, if peak widths or
33asymmetry parameters change or if you change the range of data
34that you are using in any histogram.
35<P>
36POWPREF can be run in one of three ways. It can be invoked from the
37menu item in the Powder menu (see to the left), or as a button in
38the button bar (see below) or by pressing the Alt-P key combination.
39<BR clear=left><P>
40<img src="powpref1a.gif">
41<BR>
42<P>
43<img src="powpref3a.gif">
44<BR>
45<img src="powpref4a.gif" align=left>
46Once POWPREF is started, a window is opened to watch the program
47progress, as is shown above.
48<P>
49Since POWPREF modifies the .EXP file,
50a message, as shown to the left, is displayed.
51Pressing "Load new" causes the new .EXP file to be reread.
52Pressing "Continue editing" causes EXPGUI to continue to edit the
53previous version of the .EXP file. If more changes are made, and
54the .EXP file is saved, the changes made by POWPREF will be lost.
55POWPREF makes only minor changes to the .EXP file, so there
56is little reason to reject the changes, but if a program, such
57as GENLES has made many incorrect changes to an experiment, the
58"Continue editing" option provides an easy way to keep the .EXP file
59from before the run.
60<BR clear=left>
61<P>
62<H3>GENLES</H3>
63At this point it is possible to run GENLES, to fit the initial background
64(three terms) and the scale factor (1 term).
65Similar to how POWPREF was invoked above,
66GENLES can be run from the appropriate
67button on the button bar, by typing Alt-G, or using the GENLES command
68in the Powder or Xtal menus. As soon as GENLES is started, a box appears
69on the screen showing the refinement status. (See below).
70
71<BR clear=left>
72<img src="genles2a.gif">
73
74<BR>
75<img src="powpref4a.gif" align=left>
76When GENLES is finished and the window is
77closed, press "Load new" to cause the revised .EXP
78file to be read. (Pressing "Continue editing" would
79reject the results of the refinement.)
80
81<BR clear=left>
82<P><img src="lstview1.gif">
83
84To examine the results of the refinement in more detail,
85consult the .LST file. This can be examined using the
86LSTVIEW program. This program is shown above. Note that the
87contents of the LSTVIEW box are updated as the refinement
88progresses.
89<P><BR>(.EXP Snapshot:
90<A HREF="ftp://ftp.ncnr.nist.gov/pub/cryst/gsas/tutorials/garnet4.exp">
91garnet4.exp
92</A>)
93
94<BR clear=left><HR>
95Previous step: <A HREF="garnet3.html">
96Add data (histogram) to the Experiment
97</A>
98<BR>
99Next step: <A HREF="garnet5.html">
100Plot data using POWPLOT or LIVEPLOT</A>
101
102<HR>
103</blockquote>
104<P><font size=-1><A HREF="MAILTO:crystal@NIST.gov?subject=WWW page <?=$PHP_SELF?>">Comments, corrections or questions: crystal@NIST.gov</A></font><BR>
105<font size=-1><? lastmod(); ?> </font>
106<BR>$Revision: 596 $ $Date: 2009-12-04 23:08:49 +0000 (Fri, 04 Dec 2009) $
107</body>
108</html>
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