| 1 | <html> |
|---|
| 2 | <head> |
|---|
| 3 | <META NAME="Author" CONTENT="Brian H. Toby"> |
|---|
| 4 | <title>EXPGUI Tutorial #6</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" |
|---|
| 10 | alt="Link to NIST Center for Neutron Research home page" |
|---|
| 11 | ALIGN=RIGHT></A> |
|---|
| 12 | <A HREF=http://www.nist.gov> |
|---|
| 13 | <IMG SRC="http://www.ncnr.nist.gov/images/webidblue_2lineright.gif" |
|---|
| 14 | alt="Link to National Institute of Standards & Technology home page" |
|---|
| 15 | ALIGN=LEFT></A> |
|---|
| 16 | <CENTER> |
|---|
| 17 | <A Href="http://www.ncnr.nist.gov/programs/crystallography/software/tclpkgs.html"> |
|---|
| 18 | <IMG SRC="tcltklogo100.gif" |
|---|
| 19 | alt="Link to Tcl/Tk information"> |
|---|
| 20 | </CENTER></A> |
|---|
| 21 | <hr> |
|---|
| 22 | |
|---|
| 23 | <CENTER> |
|---|
| 24 | <H1>GSAS Nickel example using EXPGUI (part 6)</H1> |
|---|
| 25 | </CENTER> |
|---|
| 26 | <H1> |
|---|
| 27 | 6. Plot data using POWPLOT or LIVEPLOT |
|---|
| 28 | </H1> |
|---|
| 29 | At this point in the GSAS tutorial |
|---|
| 30 | program POWPLOT is used to plot the diffraction data. This |
|---|
| 31 | is done in EXPGUI by pressing POWPLOT button in the button bar, or |
|---|
| 32 | by pressing the POWPLOT menu item in either the Powder menu |
|---|
| 33 | or the Graphs menu. The input supplied to POWPLOT and the |
|---|
| 34 | results are the same as what is shown in the menu, so this will |
|---|
| 35 | not be repeated here. |
|---|
| 36 | <P> |
|---|
| 37 | EXPGUI does offer another way to display diffraction data, LIVEPLOT. |
|---|
| 38 | Similar to the way POWPREF was run in the previous step, |
|---|
| 39 | LIVEPLOT can be started by pressing LIVEPLOT button in the button bar, |
|---|
| 40 | or by pressing the LIVEPLOT menu item in the Graphs menu. |
|---|
| 41 | <P> |
|---|
| 42 | <img src="liveplot1.gif" align=left> |
|---|
| 43 | Since no cycles of refinement have been run, |
|---|
| 44 | after LIVEPLOT has generated a blank window, it must be |
|---|
| 45 | triggered to read the POWPREF output by pressing the "Update Plot" |
|---|
| 46 | item in the File menu. |
|---|
| 47 | A plot similar to the one to the left is then displayed. |
|---|
| 48 | <P> |
|---|
| 49 | The contents of the LIVEPLOT window are discussed more fully |
|---|
| 50 | <A HREF="#liveplot"> |
|---|
| 51 | below</A>, but |
|---|
| 52 | note that the calculated diffraction intensities are all |
|---|
| 53 | zero at this point, since GENLES |
|---|
| 54 | has not yet been to run to simulate the pattern. |
|---|
| 55 | Likewise the background values have not yet been fit so |
|---|
| 56 | this curve is a poor fit. |
|---|
| 57 | The blue line shows the values of |
|---|
| 58 | obs-calc (diff), offset negatively. The sum of the fixed background |
|---|
| 59 | values plus the fitted background function is shown |
|---|
| 60 | difference |
|---|
| 61 | pattern is |
|---|
| 62 | <BR clear=left><P> |
|---|
| 63 | <img src="liveplot2.gif" align=left> |
|---|
| 64 | Note that the region plotted can be changed by clicking with the left |
|---|
| 65 | mouse button, to outline the region to be shown, as seen to the left. |
|---|
| 66 | When the left mouse button is pressed a second time, the graph is "zoomed in," |
|---|
| 67 | as is shown below. |
|---|
| 68 | To "zoom out" to the previous region, press the right mouse button. |
|---|
| 69 | <BR clear=left><P> |
|---|
| 70 | <img src="liveplot3.gif"> |
|---|
| 71 | <P> |
|---|
| 72 | <img src="liveplot4.gif" align=left> |
|---|
| 73 | Reflection positions can be marked, using the File/Tickmarks menu. |
|---|
| 74 | <BR clear=left><P> |
|---|
| 75 | <img src="liveplot5.gif" align=left> |
|---|
| 76 | Reflection indices can be displayed by pressing the "h" (or "H") key in the |
|---|
| 77 | position of the reflection to be labeled. The size and time before |
|---|
| 78 | the reflection labels are removed is determined by values in the Options/HKL labeling menu. |
|---|
| 79 | <BR clear=left><P> |
|---|
| 80 | <I>Do not exit LIVEPLOT at this time as it will be used again in part 8 of this |
|---|
| 81 | tutorial.</I> |
|---|
| 82 | <a name="liveplot"> |
|---|
| 83 | <H4>LIVEPLOT Contents and Options</H1> |
|---|
| 84 | </a> |
|---|
| 85 | Note that the observed data points (obs) are marked with "x" symbols in |
|---|
| 86 | LIVEPLOT. |
|---|
| 87 | This can be changed in the Options/Obs symbol menu. The simulated |
|---|
| 88 | diffraction data based on the crystallographic model (calc) is shown as |
|---|
| 89 | a red line. The lower blue line shows the values of |
|---|
| 90 | obs-calc (diff), offset negatively to avoid overlapping with the previous |
|---|
| 91 | curves. The green line (mostly obscured in this figure) shows the background |
|---|
| 92 | function (bckg). This is the sum of the fixed background |
|---|
| 93 | values (if any) plus the fitted background function (if used). |
|---|
| 94 | The dashed magenta vertical lines denote reflection positions. The color |
|---|
| 95 | and lengths of these lines can be customized using the |
|---|
| 96 | options/Configure Tickmarks menu item, for example, auto placement mode |
|---|
| 97 | creates the more customary short tickmarks placed below the pattern, |
|---|
| 98 | at different heights when more than one phase is present. |
|---|
| 99 | <P> |
|---|
| 100 | There are many other options available in LIVEPLOT in the Options menu. The |
|---|
| 101 | Appearance and location of the tickmarks can be set. The symbol and symbol size |
|---|
| 102 | used for observed data can be selected. |
|---|
| 103 | The X and Y units can be changed to Q or d-space values. Background |
|---|
| 104 | can be subtracted. The legend can be removed from the plot. |
|---|
| 105 | |
|---|
| 106 | <BR clear=left><HR> |
|---|
| 107 | Previous step: <A HREF="nickel5.html"> |
|---|
| 108 | Run POWPREF</A> |
|---|
| 109 | <BR> |
|---|
| 110 | Next step: <A HREF="nickel7.html"> |
|---|
| 111 | Setup for Least-Squares Refinement</A> |
|---|
| 112 | |
|---|
| 113 | |
|---|
| 114 | <BR clear=left> |
|---|
| 115 | <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>) |
|---|
| 116 | <BR clear=left> |
|---|
| 117 | $Revision: 209 $ $Date: 2009-12-04 23:02:13 +0000 (Fri, 04 Dec 2009) $ |
|---|
| 118 | </body> |
|---|
| 119 | </html> |
|---|
