source: trunk/tutorial1/nickel7.html @ 474

Last change on this file since 474 was 210, checked in by toby, 12 years ago

# on 2000/06/09 03:57:42, toby did:
incorporate many useful comments by Egbert Keller

  • Property rcs:author set to toby
  • Property rcs:date set to 2000/06/09 03:57:42
  • Property rcs:lines set to +7 -5
  • Property rcs:rev set to 1.3
  • Property rcs:state set to Exp
  • Property svn:keywords set to Author Date Revision Id
File size: 3.2 KB
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1<html>
2<head>
3   <META NAME="Author" CONTENT="Brian H. Toby">
4   <title>EXPGUI Tutorial #7</title>
5</head>
6<BODY BGCOLOR="#FFFFFF">
7
8<A HREF=http://www.ncnr.nist.gov>
9<IMG SRC="http://www.ncnr.nist.gov/images/ncnrtrans.gif" 
10alt="Link to NIST Center for Neutron Research home page"
11ALIGN=RIGHT></A>
12<A HREF=http://www.nist.gov>
13<IMG SRC="http://www.ncnr.nist.gov/images/webidblue_2lineright.gif" 
14alt="Link to National Institute of Standards & Technology home page"
15ALIGN=LEFT></A>
16<CENTER>
17<A Href="http://www.ncnr.nist.gov/programs/crystallography/software/tclpkgs.html">
18<IMG SRC="tcltklogo100.gif" 
19alt="Link to Tcl/Tk information">
20</CENTER></A>
21<hr>
22
23<CENTER>
24<H1>GSAS Nickel example using EXPGUI (part 7)</H1>
25</CENTER>
26<H1>
277. Setup for Least-Squares Refinement
28</H1>
29
30Before the model can be refined to better fit the data, the
31structure must be entered. When starting with a new model
32it is a good idea to refine the scale factors for each histogram
33and the background terms before refining any structural parameters.
34So EXPGUI will be used to check which parameters are set to be refined.
35
36<img src="addatom1.gif" align=left>
37Select a phase by pressing the "1" button in the upper left.
38Then add an atom to the model by pressing the "Add New Atom" button
39in the lower right side of the Phase pane
40<a href="nickel2.html#phasepane">(shown in part 2)</a>.
41After entering the atom type, the
42coordinates added, and changing the Uiso value to match the example,
43press "Add" to add the atom to the .EXP file.
44<BR clear=left><P>
45<img src="addatom2.gif" align=left>
46A box then appears, as shown to the left, to show the results when the atom is read into EXPTOOL.
47<BR clear=left><P>
48<img src="addatom3.gif">
49<BR clear=left>
50Note that the atom now appears on the phase page. Also note that the cell
51will not be refined, since the "Refine Cell" checkbutton in the upper right
52is not checked. Nor are any atomic parameters being refined, since X V and F
53do not appear in the ref./damp column.
54<BR clear=left>
55<P>
56<img src="bkg1.gif">
57<BR clear=left>
58We then check each histogram from the Histogram pane, and see that
59the background function has been set to type 4, with 4 terms, as recommended
60in the tutorial, and that no diffractometer constants will be refined
61(above and below).
62<BR clear=left>
63<img src="bkg2.gif">
64<BR clear=left>
65<P>
66<img src="scale1.gif">
67<BR clear=left>
68We can quickly confirm that the scale factors for the two
69histograms will be refined on the Scaling pane
70(above and below).
71<BR clear=left>
72<img src="scale2.gif">
73<BR clear=left>
74<P>
75<img src="prof1.gif">
76<BR clear=left>
77Finally we check that no profile terms are being refined on the Profile
78panes.
79(above and below).
80<BR clear=left>
81<img src="prof2.gif">
82<BR clear=left>
83
84<P><BR>(.EXP Snapshot:
85<A HREF="ftp://ftp.ncnr.nist.gov/pub/cryst/gsas/tutorials/nickel7.exp">
86nickel7.exp
87</A>)
88
89
90<BR clear=left><HR>
91Previous step: <A HREF="nickel6.html">
92Plot data using POWPLOT or LIVEPLOT</A>
93<BR>
94Next step: <A HREF="nickel8.html">
95Run GENLES</A>
96
97<BR clear=left>
98<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>)
99<BR clear=left>
100$Revision: 210 $ $Date: 2009-12-04 23:02:14 +0000 (Fri, 04 Dec 2009) $
101</body>
102</html>
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