Calibration fit: CeO₂, PEARL¶

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-neut-tof_ceo2-pearl-ceo2

Load the experiment¶

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

• pd-neut-tof_ceo2-pearl-pearl

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 and time-of-flight calibration¶

CeO₂ is the calibration standard, so its cell stays fixed and the DIFC terms put the peaks in place.

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

Background¶

The six polynomial terms 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.

Gaussian widths¶

The Gaussian terms that grow with d spacing.

Filter the Peak broadening parameters with sigma_1 in their name using the category filter and the name filter and the Peak broadening parameters with sigma_2 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.

Lorentzian width¶

The Lorentzian term that grows with d spacing.

Filter the Peak broadening parameters with gamma_1 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¶

The back-to-back exponentials that shape each time-of-flight peak.

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¶

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.

Absorption¶

Absorption weakens the intensities with time of flight, as the displacements do, so it comes after them, on its own.

Filter the Absorption 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.