Sequential magnetic fit: Co₂SiO₄, D20 scan from 2.3 K¶

The same staged fit as the Python and Command line tutorials, in the app. A scan's patterns come with its project, so open it from EasyDiffraction's collection with Project → Examples; each stage frees its parameters in the Parameters table on Analysis before the fit.

Open the example¶

Press Start on Home, search Examples on Project for pd-neut-cwl_cosio-d20_scan-213f and open it.

Fit the template first¶

On Analysis → Extra, set the fitting mode to single, so the stages fit the template pattern alone.

Set the minimizer¶

On Analysis → Extra, set the Minimizer as the case's project does: the Shift/s.u. stop rule and room for more iterations.

Start with nothing free¶

On Analysis, open the Free column header of the Parameters table and fix every parameter, so the stages below free one group at a time.

Scale, 2θ zero and cell¶

Filter the Linked structures and Cell parameters, one category at a time, using the category filter and the Instrument parameters with calib in their name using the category filter and the name filter, click the Free column header and choose Free · all, then press Fit in the status bar.

Background¶

The sixteen background points follow the level between the peaks.

Filter the Background parameters using the category filter, click the Free column header and choose Free · all, then press Fit in the status bar.

Peak widths¶

U, V and W only: across a temperature scan the Lorentzian term and the asymmetry stay at their 2.3 K values, as do the form factor's j2 term.

Filter the Peak broadening parameters with gauss in their name using the category filter and the name filter, click the Free column header and choose Free · all, then press Fit in the status bar.

Atom positions¶

Filter the Atomic coordinates parameters using the category filter, click the Free column header and choose Free · all, then press Fit in the status bar.

Displacements¶

Co2's displacement follows Co1's by the project's constraint.

Filter the Atomic displacement parameters using the category filter, click the Free column header and choose Free · all, then press Fit in the status bar.

Magnetic moments¶

Last, the moments: Co1 in any direction, Co2 along b.

Filter the Magnetic moments parameters using the category filter, click the Free column header and choose Free · all, then press Fit in the status bar.

Fit the scan¶

Back on Analysis → Extra, set the fitting mode to sequential and press Fit: every pattern is fitted in turn, each from the fit before it.

Choose a dataset¶

On Experiment, use the selector above the pattern or the Experiments table to select a measurement. The selector supports searching in a long series.

Before fitting, the pattern uses the template settings. After fitting, selecting a dataset shows its fitted values and updates the relevant structure values too.

Choose the starting-point rule¶

On Analysis → Extra, expand Fitting mode. Sequential starts each dataset from the preceding result; Independent starts each from the same template. Single fits only the shown dataset and makes that result the new template.

Check the template before running the full series. See fitting modes for the starting-state rules.

Inspect the scan declaration¶

Expand Sequential fit and Scan extraction rules on the same tab. Inspect the data directory, file pattern, order and rules used to extract values such as temperature from the measurement files. These groups show the saved scan declaration.

Run, stop and continue¶

Press Fit at the right of the status bar, on any page, and follow the dataset counts beside it. While a run is under way the button reads Stop; stopping keeps the completed results. It then reads Continue, which resumes from the first unfitted file, or Refit after a change to the template, which fits every file again. Reset, next to it, clears every dataset's result for another run, and Undo restores the preceding results.

Follow, also in the status bar, displays the dataset currently being fitted. Selecting another dataset turns it off; select Follow again to follow progress. Display and updates controls redraw frequency.

Inspect the scan views¶

Use Stacked to compare the patterns one above another or Map to inspect intensity across the series as rows of colour. On Stacked, Spacing runs from Overlay, every pattern on one baseline, through Close, Medium and Wide, the default, to Separate, each pattern in its own band. Its legend, turned on from the toolbar, lists the files; click an entry to hide that pattern. On Map, choose the colour map, Blue-Red by default or Viridis, Batlow, Inferno, Lapaz or Greys, and its Direction: Auto, Normal or Inverted. Subtract background draws each pattern less the project's background, here and on the pattern chart. Evolution plots a fitted parameter with its uncertainty against a selected dataset value or its place in the scan. Select a point to inspect that dataset elsewhere in the app.

Correlations shows the selected dataset's last fit. Only the template dataset's correlations are retained when saving and reopening the project. After editing the template, earlier results remain visible but are marked out of date until refitted.

Save the scan¶

Use Save project as… to keep the example together with its data and results. The run writes a row per dataset to analysis/results.csv as it progresses. Inspect the scan's report on Report and choose which sections to export.

Correlations¶

The Correlations view on Analysis shows which fitted parameters move together.

Report¶

The Report page collects the structure, the experiment and the fit.