source: trunk/tutorial1/nickel7.html @ 163

Last change on this file since 163 was 163, checked in by toby, 12 years ago

# on 2000/05/26 16:08:48, toby did:
GSAS Nickel tutorial in EXPGUI

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  • Property rcs:date set to 2000/05/26 16:08:48
  • Property rcs:rev set to 1.1
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[163]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>
37First an atom is added to the model by pressing the "Add New Atom" button
38in the lower left of the Phase pane.
39After the atom type, the
40coordinates are added, and the Uiso value is changed,
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<img src="bkg2.gif">
61<BR clear=left>
62<P>
63<img src="scale1.gif">
64<BR clear=left>
65We can quickly confirm that the scale factors for the two
66histograms will be refined on the Scaling pane
67(above and below).
68<img src="scale2.gif">
69<BR clear=left>
70<P>
71<img src="prof1.gif">
72<BR clear=left>
73Finally we check that no profile terms are being refined on the Profile
74panes.
75(above and below).
76<img src="prof2.gif">
77<BR clear=left>
78
79<P><BR>(.EXP Snapshot:
80<A HREF="ftp://ftp.ncnr.nist.gov/pub/cryst/gsas/tutorials/nickel7.exp">
81nickel7.exp
82</A>)
83
84
85<BR clear=left><HR>
86Previous step: <A HREF="nickel6.html">
87Plot data using POWPLOT or LIVEPLOT</A>
88<BR>
89Next step: <A HREF="nickel8.html">
90Run GENLES</A>
91
92<BR clear=left>
93<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>)
94<BR clear=left>
95$Revision: 163 $ $Date: 2009-12-04 23:01:27 +0000 (Fri, 04 Dec 2009) $
96</body>
97</html>
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