| 1 | <html> |
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| 2 | <head> |
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| 3 | <META NAME="Author" CONTENT="Brian H. Toby"> |
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| 4 | <title>EXPGUI Tutorial #5</title> |
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| 5 | </head> |
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| 6 | <BODY BGCOLOR="#FFFFFF"> |
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| 7 | |
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| 8 | <A HREF=http://www.ncnr.nist.gov> |
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| 9 | <IMG SRC="http://www.ncnr.nist.gov/images/ncnrtrans.gif" |
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| 10 | alt="Link to NIST Center for Neutron Research home page" |
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| 11 | ALIGN=RIGHT></A> |
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| 12 | <A HREF=http://www.nist.gov> |
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| 13 | <IMG SRC="http://www.ncnr.nist.gov/images/webidblue_2lineright.gif" |
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| 14 | alt="Link to National Institute of Standards & Technology home page" |
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| 15 | ALIGN=LEFT></A> |
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| 16 | <CENTER> |
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| 17 | <A Href="http://www.ncnr.nist.gov/programs/crystallography/software/tclpkgs.html"> |
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| 18 | <IMG SRC="tcltklogo100.gif" |
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| 19 | alt="Link to Tcl/Tk information"> |
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| 20 | </CENTER></A> |
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| 21 | <hr> |
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| 22 | |
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| 23 | <CENTER> |
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| 24 | <H1>GSAS Nickel example using EXPGUI (part 5)</H1> |
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| 25 | </CENTER> |
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| 26 | <H1> |
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| 27 | 5. Run POWPREF |
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| 28 | </H1> |
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| 29 | <img src="powpref2.gif" align=left> |
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| 30 | Before a least-squares refinement can be run, the POWPREF program |
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| 31 | must be run. This program assigns the reflections that are associated with |
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| 32 | each data point in each histogram. For this reason, POWPREF should |
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| 33 | be rerun if the lattice constants change, if peak widths or |
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| 34 | asymmetry parameters change or if you change the range of data |
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| 35 | that you are using in any histogram. |
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| 36 | <P> |
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| 37 | POWPREF can be run in one of three ways. It can be invoked from the |
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| 38 | menu item in the Powder menu (see to the left), or as a button in |
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| 39 | the button bar (see below) or by pressing the Alt-P key combination. |
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| 40 | <BR clear=left><P> |
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| 41 | <img src="powpref1.gif"> |
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| 42 | <BR> |
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| 43 | <P> |
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| 44 | <img src="powpref3.gif"> |
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| 45 | <BR> |
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| 46 | <img src="powpref4.gif" align=left> |
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| 47 | Once POWPREF is started, a window is opened to watch the program |
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| 48 | progress, as is shown above. |
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| 49 | <P> |
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| 50 | Since POWPREF modifies the .EXP file, |
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| 51 | a message, as shown to the left, is displayed. |
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| 52 | Pressing "Load new" causes the new .EXP file to be reread. |
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| 53 | Pressing "Continue editing" causes EXPGUI to continue to edit the |
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| 54 | previous version of the .EXP file. If more changes are made, and |
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| 55 | the .EXP file is saved, the changes made by POWPREF will be lost. |
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| 56 | POWPREF makes only minor changes to the .EXP file, so there |
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| 57 | is little reason to reject the changes, but if a program, such |
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| 58 | as GENLES has made many incorrect changes to an experiment, the |
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| 59 | "Continue editing" option provides an easy way to keep the .EXP file |
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| 60 | from before the run. |
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| 61 | |
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| 62 | <P><BR>(.EXP Snapshot: |
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| 63 | <A HREF="ftp://ftp.ncnr.nist.gov/pub/cryst/gsas/tutorials/nickel5.exp"> |
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| 64 | nickel5.exp |
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| 65 | </A>) |
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| 66 | |
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| 67 | <BR clear=left><HR> |
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| 68 | Previous step: <A HREF="nickel4.html"> |
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| 69 | Change a profile parameter |
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| 70 | </A> |
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| 71 | <BR> |
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| 72 | Next step: <A HREF="nickel6.html"> |
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| 73 | Plot data using POWPLOT or LIVEPLOT</A> |
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| 74 | |
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| 75 | <BR clear=left> |
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| 76 | <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>) |
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| 77 | <BR clear=left> |
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| 78 | $Revision: 161 $ $Date: 2009-12-04 23:01:25 +0000 (Fri, 04 Dec 2009) $ |
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| 79 | </body> |
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| 80 | </html> |
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