Two-phase fit: La₀.₅Ba₀.₅CoO₃ and Si, McStas¶

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 structures¶

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

• pd-neut-tof_lbco-si-mcstas-lbco
• pd-neut-tof_lbco-si-mcstas-si

Load the experiment¶

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

• pd-neut-tof_lbco-si-mcstas-mcstas

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.

Scales and cells¶

Both phases' scales and cells put the peaks in place and at the right height; the DIFC stays fixed, as in diffraction-lib's tutorial.

Filter the Linked structures parameters of mcstas, choosing each in the datablock filter using the category filter and the Cell parameters of lbco and si, choosing each in the datablock filter using the category filter, click the Free column header and choose Free · all, then press Fit in the status bar.

Background¶

Choose mcstas in the datablock filter, then 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¶

Choose mcstas in the datablock filter, then filter the Peak broadening parameters with sigma 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.

Rise and decay¶

Choose mcstas in the datablock filter, then filter the Peak asymmetry parameters using the category filter, click the Free column header and choose Free · all; then type alpha_0 in the name filter and choose Fixed · all in the same menu, then press Fit in the status bar.

Displacements¶

Co's and O's; La's, Ba's and Si's stay fixed, as the case's project keeps them.

Choose lbco in the datablock filter, then filter the Atomic displacement parameters using the category filter, click the Free column header and choose Free · all; then type [Ba] in the name filter and choose Fixed · all in the same menu; then type [La] in the name filter and choose Fixed · all in the same menu, 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.