source: trunk/tutorial2/RCS/garnet8.html,v @ 932

Last change on this file since 932 was 932, checked in by toby, 12 years ago

address missing files

File size: 3.7 KB
Line 
1head    1.3;
2access;
3symbols;
4locks
5        toby:1.3; strict;
6comment @# @;
7
8
91.3
10date    2002.04.12.21.34.08;    author toby;    state Exp;
11branches;
12next    1.2;
13
141.2
15date    2000.06.01.16.07.21;    author toby;    state Exp;
16branches;
17next    1.1;
18
191.1
20date    2000.05.30.22.22.38;    author toby;    state Exp;
21branches;
22next    ;
23
24
25desc
26@Garnet tutorial
27@
28
29
301.3
31log
32@remove id info; update format
33@
34text
35@<html>
36<head>
37   <title>EXPGUI Tutorial #8</title>
38</head>
39
40<style>
41A:link {text-decoration:none}
42A:vlink {text-decoration:none}
43</style>
44
45<BODY BGCOLOR="#FFFFFF"
46      topmargin="0" leftmargin="0" marginwidth="0" marginheight="0"
47      text="#000000" link="#0033ff" vlink="#0033ff" alink="#0033ff">
48
49<?
50   include("/var/www/include/navigation.inc");
51   include("/var/www/include/utility.inc");
52?>
53<blockquote>
54
55<CENTER>
56<H1>EXPGUI Tutorial: Garnet (part 8)</H1>
57</CENTER>
58<H1>
598. Vary atomic parameters
60</H1>
61Now that parameters have been appropriately constrained, they can be varied.
62Below all atoms are selected (using a mouse drag or a right-mouse click)
63and the "U" and "X" flags are set, so that all allowed coordinates and
64all isotropic displacement parameters are set to be varied. Note that
65all but the last atom are located on special positions where the
66coordinates are fixed
67by symmetry.
68Thus, it makes no difference if the "X" flag is set for the
69first five atoms.
70<BR clear=left><P>
71<img src="varatom1.gif">
72<BR clear=left><P>
73The four shared-site atoms are selected and the "F" (fractional occupancy)
74flag is set for those atoms.
75<BR clear=left><P>
76<img src="varatom2.gif">
77<BR clear=left>
78At this point GENLES can be run.
79<BR clear=left><P>
80<img src="varatom3.gif">
81<BR clear=left><P>
82Significant improvement is noted, both by agreement factors (see above)
83and from the plot (below).
84<BR clear=left><P>
85<img src="varatom4.gif">
86<BR clear=left>
87Still more improvement (see below)
88can be obtained by allowing the first four profile
89parameters (U, V, W and asym) and increasing the number of
90background terms. For CW neutron
91data, I recommend background function #1, the Chebychev polynomial function,
92and 6-10 terms, for a fairly flat background such as this.
93
94<BR clear=left><P>
95<img src="varatom5.gif">
96<BR clear=left>
97
98<P><BR>(.EXP Snapshot:
99<A HREF="ftp://ftp.ncnr.nist.gov/pub/cryst/gsas/tutorials/garnet8.exp">
100garnet8.exp
101</A>)
102
103<BR clear=left><HR>
104Previous step: <A HREF="garnet7.html">
105Define constraints
106</A>
107<BR>
108Next step: <A HREF="garnet9.html">
109Compute Bond Distances and Angles</A>
110
111<HR>
112</blockquote>
113<P><font size=-1><A HREF="MAILTO:crystal@@NIST.gov?subject=WWW page <?=$PHP_SELF?>">Comments, corrections or questions: crystal@@NIST.gov</A></font><BR>
114<font size=-1><? lastmod(); ?> </font>
115<BR>$Revision: 1.4 $ $Date: 2002/04/12 21:21:18 $
116</body>
117</html>
118@
119
120
1211.2
122log
123@correct typos
124@
125text
126@a2 1
127   <META NAME="Author" CONTENT="Brian H. Toby">
128a4 1
129<BODY BGCOLOR="#FFFFFF">
130d6 14
131a19 14
132<A HREF=http://www.ncnr.nist.gov>
133<IMG SRC="http://www.ncnr.nist.gov/images/ncnrtrans.gif"
134alt="Link to NIST Center for Neutron Research home page"
135ALIGN=RIGHT></A>
136<A HREF=http://www.nist.gov>
137<IMG SRC="http://www.ncnr.nist.gov/images/webidblue_2lineright.gif"
138alt="Link to National Institute of Standards & Technology home page"
139ALIGN=LEFT></A>
140<CENTER>
141<A Href="http://www.ncnr.nist.gov/programs/crystallography/software/tclpkgs.html">
142<IMG SRC="tcltklogo100.gif"
143alt="Link to Tcl/Tk information">
144</CENTER></A>
145<hr>
146d77 5
147a81 4
148<BR clear=left>
149<HR><p><a href="http://www.ncnr.nist.gov/staff/toby/">Brian Toby</a> (<a href="mailto:brian.toby@@nist.gov">Brian.Toby@@NIST.GOV</a>)
150<BR clear=left>
151$Revision: 1.1 $ $Date: 2000/05/30 22:22:38 $
152@
153
154
1551.1
156log
157@Initial revision
158@
159text
160@d60 1
161a60 1
162and 6-10 terms, for a fairily flat background such as this.
163d82 1
164a82 1
165$Revision: 1.1 $ $Date: 2000/05/26 16:08:48 $
166@
Note: See TracBrowser for help on using the repository browser.