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| 3 | <title>EXPGUI Tutorial #7</title> |
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| 15 | <? |
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| 16 | include("/var/www/include/navigation.inc"); |
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| 17 | include("/var/www/include/utility.inc"); |
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| 18 | ?> |
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| 19 | <blockquote> |
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| 20 | |
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| 21 | <CENTER> |
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| 22 | <H1>GSAS Nickel example using EXPGUI (part 7)</H1> |
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| 23 | </CENTER> |
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| 24 | <H1> |
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| 25 | 7. Setup for Least-Squares Refinement |
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| 26 | </H1> |
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| 27 | |
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| 28 | Before the model can be refined to better fit the data, the |
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| 29 | structure must be entered. When starting with a new model |
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| 30 | it is a good idea to refine the scale factors for each histogram |
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| 31 | and the background terms before refining any structural parameters. |
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| 32 | So EXPGUI will be used to check which parameters are set to be refined. |
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| 33 | |
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| 34 | <img src="addatom1.gif" align=left> |
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| 35 | Select a phase by pressing the "1" button in the upper left. |
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| 36 | Then add an atom to the model by pressing the "Add New Atom" button |
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| 37 | in the lower right side of the Phase pane |
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| 38 | <a href="nickel2.html#phasepane">(shown in part 2)</a>. |
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| 39 | After entering the atom type, the |
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| 40 | coordinates added, and changing the Uiso value to match the example, |
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| 41 | press "Add" to add the atom to the .EXP file. |
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| 42 | <BR clear=left><P> |
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| 43 | <img src="addatom2.gif" align=left> |
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| 44 | A box then appears, as shown to the left, to show the results when the atom is read into EXPTOOL. |
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| 45 | <BR clear=left><P> |
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| 46 | <img src="addatom3.gif"> |
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| 47 | <BR clear=left> |
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| 48 | Note that the atom now appears on the phase page. Also note that the cell |
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| 49 | will not be refined, since the "Refine Cell" checkbutton in the upper right |
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| 50 | is not checked. Nor are any atomic parameters being refined, since X V and F |
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| 51 | do not appear in the ref./damp column. |
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| 52 | <BR clear=left> |
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| 53 | <P> |
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| 54 | <img src="bkg1.gif"> |
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| 55 | <BR clear=left> |
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| 56 | We then check each histogram from the Histogram pane, and see that |
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| 57 | the background function has been set to type 4, with 4 terms, as recommended |
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| 58 | in the tutorial, and that no diffractometer constants will be refined |
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| 59 | (above and below). |
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| 60 | <BR clear=left> |
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| 61 | <img src="bkg2.gif"> |
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| 62 | <BR clear=left> |
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| 63 | <P> |
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| 64 | <img src="scale1.gif"> |
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| 65 | <BR clear=left> |
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| 66 | We can quickly confirm that the scale factors for the two |
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| 67 | histograms will be refined on the Scaling pane |
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| 68 | (above and below). |
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| 69 | <BR clear=left> |
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| 70 | <img src="scale2.gif"> |
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| 71 | <BR clear=left> |
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| 72 | <P> |
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| 73 | <img src="prof1.gif"> |
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| 74 | <BR clear=left> |
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| 75 | Finally we check that no profile terms are being refined on the Profile |
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| 76 | panes. |
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| 77 | (above and below). |
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| 78 | <BR clear=left> |
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| 79 | <img src="prof2.gif"> |
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| 80 | <BR clear=left> |
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| 81 | |
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| 82 | <P><BR>(.EXP Snapshot: |
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| 83 | <A HREF="ftp://ftp.ncnr.nist.gov/pub/cryst/gsas/tutorials/nickel7.exp"> |
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| 84 | nickel7.exp |
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| 85 | </A>) |
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| 86 | |
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| 87 | |
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| 88 | <BR clear=left><HR> |
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| 89 | Previous step: <A HREF="nickel6.html"> |
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| 90 | Plot data using POWPLOT or LIVEPLOT</A> |
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| 91 | <BR> |
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| 92 | Next step: <A HREF="nickel8.html"> |
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| 93 | Run GENLES</A> |
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| 94 | |
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| 95 | <HR> |
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| 96 | </blockquote> |
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| 97 | <P><font size=-1><A HREF="MAILTO:crystal@NIST.gov?subject=WWW page <?=$PHP_SELF?>">Comments, corrections or questions: crystal@NIST.gov</A></font><BR> |
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| 98 | <font size=-1><? lastmod(); ?> </font> |
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| 99 | <BR>$Revision: 589 $ $Date: 2009-12-04 23:08:42 +0000 (Fri, 04 Dec 2009) $ |
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| 100 | </body> |
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| 101 | </html> |
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