rietx
rietx is an open-source Rietveld refinement and pattern analysis Python module with a streamlined API designed for those who want to drive refinements from code.
Installation
pip install rietx # Python >= 3.11; numpy/scipy core, compiled kernels, matplotlib figures
Example refinement
Condensed from examples/nac_11bm.py,
which fits APS 11-BM synchrotron data on Na₂Ca₃Al₂F₁₄ with a CaF₂ impurity.
import rietx as rx
data = rx.read_pattern("11BM_NAC.fxye") # esd column read from file
structure = rx.Structure.from_cif("cod_1000236.cif")
instrument = rx.Instrument.debye_scherrer(wavelength=0.4139090)
ref = rx.Refinement(structure, instrument)
# structure-free Le Bail first: cell + profile + background
lebail = ref.fit(data, mode="lebail", two_theta_limits=(2, 24))
# then Rietveld under the staged turn-on order of McCusker et al. (1999)
result = ref.fit(data, plan="mccusker_default", two_theta_limits=(2, 24))
report = rx.build_report(result) # numbers, not pixels
result.plot(path="fit.png") # obs/calc/diff/ticks
Output of the full script (trimmed at the …):
Le Bail: status=converged Rwp=0.1436 GoF=5.44 a=10.251213 A
Rietveld: status=converged Rwp=0.0930 GoF=3.53
a = 10.251216 +/- 0.000039 A (COD reference 10.257(1); high-accuracy powder ~10.2497-10.2506)
warning[FLOOR_HIT]: phases.1.atoms.0.biso refined to its floor (ρ=+0.188).
info[CAPILLARY_OFFSET_UNAVAILABLE]: This capillary geometry declares no goniometer radius, …
FitReport: 53 misfit regions. The top 15 carry 74% of χ² and the other 38 carry 15%.
region 14.22- 14.54 deg localRwp=0.154 chi2share=13.7% max|d/sig|=49.6
…
Refinement history (every stage is a restorable checkpoint):
t5544a638 15 nodes data=11BM_NAC.fxye
n0000 root —
n0001 stage:bkg Rwp 3.1772
…
*n0014 stage:closing Rwp 0.0930
Current features
- Multi-phase Rietveld, Le Bail and Pawley
- X-ray and constant-wavelength neutron data
- Magnetic refinement (in progress)
- Joint refinement of several patterns
- Preset staged plans
- Extensively documented forward model
- Corrections: axial divergence, displacement and
transparency, absorption, preferred orientation, anisotropic displacement and strain,
anomalous dispersion
- Constraints and restraints
- Quantitative phase analysis
- Multiple solvers
- Optional JAX & torch differentiable backends
- Readers for many standard formats including
.xy/.xye, GSAS raw, pdCIF, .chi, Rigaku .ras/.rasx, Bruker
.uxd/.brml/.raw, PANalytical .xrdml/.udf and Philips .rd/.sd
- Another program's refinement, read in:
read_project_model opens a TOPAS .inp or a FullProf .pcr by content,
refine flags included
- Writers for TOPAS, FullProf, GSAS and GSAS-II files
Validation
Validation suites are run in CI against real data. Details here: docs/VALIDATION.md
Documentation
Development
git clone https://github.com/yue-here/rietx && cd rietx
uv venv --python 3.12 && uv pip install -e ".[dev]"
.venv/bin/python -m pytest -n auto --dist loadgroup -m "not slow" # ~1-3 min
.venv/bin/python -m pytest -n auto --dist loadgroup # + real-data acceptance, ~15-30 min
.venv/bin/python -m ruff check src tests examples
--dist loadgroup is required to keep shared expensive fixtures on one
worker. For the test ladder and style see
CONTRIBUTING.md, and AGENTS.md if your
contributor is an agent.
License and credits
MIT. Algorithms are independently implemented from the published literature, with sources cited in the manual. A full list of sources is also provided in
ATTRIBUTION.md,
and test-data provenance is listed in
tests/data/README.md.
CIF and symmetry handling uses
gemmi. To cite the package, use
CITATION.cff.
