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Refine Panel

The fourth sidebar tab controls the Rietveld refinement model. It has two modes, switched by the segmented control at the top:

  • Quick (default) — sensible defaults, nothing to configure.
  • Advanced — exposes every parameter below.

Quick first, Advanced after

Run the phase search in Quick mode. The search Rietveld-refines every candidate combination, so a heavier model slows the whole tree search and gains you nothing while the phases are still unknown. Once the search has identified the phases, switch to Advanced and re-refine the chosen solution with the extra parameters (zero-point, asymmetry, broadening, orientation…) to polish the final fit.

Refine panel (Advanced mode)

Refined parameters

Each row is a checkbox (refine on/off) plus a ± range field that bounds the parameter during refinement:

Parameter BGMN name Default Refines
Zero-point shift EPS1 off · ± 0.02 The 2θ zero-point error of the goniometer
Sample height EPS2 on · ± 0.05 Specimen displacement from the focusing circle
Peak asymmetry k1, k2 off · ≤ 0.01 Low-angle peak asymmetry
Size broadening b1 off · ≤ 0.01 Crystallite-size peak broadening

Lattice flexibility (0 – 50 %, default 10 %) sets how far each phase's lattice parameters may deviate from its CIF values.

Preferred orientation & profile

Control Options
Pref. orientation Off · Basic (SPHAR0) · Advanced (SPHAR4 spherical harmonics)
Profile RP 1 – RP 4 (default RP 4) — the BGMN profile complexity level

Background

  • Subtract background — toggle background handling on/off.
  • Auto — an iterative polynomial fit; the Polynomial degree spin box (1 – 12, default 5) controls its flexibility.
  • Manual — you place the background yourself by dragging anchor points on the preview plot (see Pattern Preview). Reset points re-seeds the anchors from the auto fit.

Phases in refinement & re-refining

The phase list at the bottom powers the re-refinement workflow:

  1. Run a phase search and open a solution you like.
  2. The solution's phases are loaded into this list automatically.
  3. Edit the list — remove a dubious phase or Add phase CIF — then click Refine phases.
  4. A single refinement runs with exactly the listed phases (no search), and the result appears as a new solution.

Tip

This is the fastest way to test "what if I drop this minor phase?" or to refine a known phase assemblage directly — it skips the combinatorial search entirely. The same operation is exposed as start_refinement on the MCP server.