Changeset 3604

Ignore:
Timestamp:
Sep 15, 2018 7:55:29 PM (4 years ago)
Message:

update tutorial

Location:
Tutorials/SimpleMagnetic
Files:
57 edited

Unmodified
Removed
• Tutorials/SimpleMagnetic/SimpleMagnetic.htm

 r3559 Von Dreelevondreele1862022062242017-08-09T17:16:00Z2018-07-18T19:51:00Z2018-09-16T00:43:00Z15837

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The order of operations for the transformation is given at the top of the window; the U vector permits applying an origin shift to the atom coordinates before the transformation and the V vector is for an origin shift after the transformation. The lattice parameters are transformed by changing the metric tensor via

the top of the window; the U vector permits applying an origin shift to the atom coordinates before the transformation and the V vector is for an origin shift after the transformation. The lattice parameters are transformed by changing the metric tensor via

The dialog box gives an extensive list of commonly used transformations for e.g. swapping axes. In this case we are not transforming the unit cell so the matrix is just the unit matrix (ones on diagonal) and we are not shifting the origin so U & V are zeros. We do want the new phase to be magnetic so press the Make new

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This allows one to select possible magnetic lattice centering operations as given by the BNS nomenclature. This can be needed if one had discovered a requirement of doubling a cell axis in the previous step (e.g. a nonzero propagation vector). This is not required in this case and we are using the space group (Pnma) for the magnetic cell. Leave the box at the bottom about constraints checked as we want them to tie the two phases together.  Press Pnma) for the magnetic cell. Leave the box at the bottom about constraints checked as we want them to tie the two phases together.  Press

This gives the constraints between the two phases for scale factors (e.g. phase fractions) and the size & mustrain sample broadening terms. NB: this assumes isotropic modelling of both because the original LaMnO3 src="SimpleMagnetic_files/image098.png" v:shapes="_x0000_i1078">

This gives the constraints between the two phases for scale factors (e.g. phase fractions) and the size & mustrain sample broadening terms. NB: this assumes isotropic modelling of both because the original LaMnO3 was modeled that way. If you want to use one of the more complex sample broadening models, you will have to revisit this tab and put in the appropriate

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The boxes that carry the magnetic moment components (

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It now shows the magnetic space group as Pnma.

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with 0.0 in each of the magnetic

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Under the

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Scroll down to the bottom and select

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The least squares will not begin a refinement of

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There does not appear to be any calculated magnetic

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The magnetic moment is clearly too small; to let the least

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This appears to be a reasonable solution; a more complete

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Now set the spin operators to all 

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You can see in particular at the pair of peaks at 33.3 and

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Looking at the plot, it would seem that the lattice

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Since the scan covers a very wide range in 2

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Now we can add refinement of the atom positions and thermal

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This curve shows a couple of peaks which are from some

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The plot will show the unit cell contents of

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This completes this tutorial; you can save the project if

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and the

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Step 2: Select Limits

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Step 3: Read in the chemical structure for

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Select the histogram (or press

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Notice that the space group from

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This

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Note
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Then check the box Because

In the previous step we did not have to resort to any doubling of a cell axis to explain the suite of magnetic reflections, so the propagation vector is zero (in case anyone asks!). To make the magnetic cell from the chemical cell we will use the transform tool that is in GSAS-II in the General tab for the chemical structure. That tab is

doubling of a cell axis to explain the suite of magnetic reflections, so the propagation vector is zero (in case anyone asks!). To make the magnetic cell from the chemical cell we will use the transform tool that is in GSAS-II in the General tab for the chemical structure. That tab is

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Under the

The order of operations for the transformation is given at

This allows one to select possible magnetic lattice

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This allows one to reject certain atoms that are known to

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The phase is named with mag appended to the end, the phase

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Notice

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The

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If

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Clearly

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Then do

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and the magnetic moment components

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So we test the next possibility.

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The

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Lets test the next one.

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The

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We should now check the last spin configuration.

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and with the strong

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well. The do Calculate/Refine for each one. After several cycles of refinement I find the rrb minor-latin;mso-bidi-theme-font:minor-latin'>Calculate/Refine
for each one. After several cycles of refinement I find the rrb model Rwp=7.615%, the rbr model Rwp=7.716% and the brr

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The magnetic peaks contributing to this peak are the 200,221

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which shows that the ferromagnetic

• Tutorials/SimpleMagnetic/SimpleMagnetic_files/filelist.xml

 r3482
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