Rietveld fit: high-entropy perovskite, P02.1¶

The same staged fit as the Python and Command line tutorials, in the app. Its structure and experiment come from EasyDiffraction's collection with Load ▾ From web…, and each stage frees its parameters in the Parameters table on Analysis before the fit.

Create a project¶

Press Start on Home, then Create a new project, and give it a name.

Load the structure¶

On Structure, choose Load ▾ From web…, search for each entry by its id and click it:

• pd-xray-cwl_lam7o3-p021-lam7o3

Load the experiment¶

On Experiment, choose Load ▾ Full experiment From web…, search for each entry by its id and click it:

• pd-xray-cwl_lam7o3-p021-p021

Add the relations¶

The project ties some parameters together from the start. On Analysis → Extra, add the aliases and constraints.

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¶

The scale, the zero shift and the cell put the peaks in place and at the right height.

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¶

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¶

The Gaussian widths and the Lorentzian X.

Filter the Peak profile parameters using the category filter, click the Free column header and choose Free · all; then type lorentz_y in the name filter and choose Fixed · all in the same menu, then press Fit in the status bar.

Background from the fitted model¶

With a fitted peak model, estimate the background again with the calculated peaks subtracted, which follows the low-angle background better, then free the new points and fit again.

Filter the Background parameters using the category 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¶

La's, the mixed site's (through Ti) and O1's; O2's follows O1's.

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.

Correlations¶

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

Report¶

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