Skip to content

Features

EasyDiffraction calculates diffraction patterns from a structural model and instrument settings, and refines that model against measured data. This page gives a complete overview of what it can do today and what is planned, across powder and single-crystal diffraction, total scattering (PDF), and the analysis tools around them.

Calculation engines

Most of the physics is computed by a pluggable calculation engine. Each engine is described on the Analysis page.

  • cryspy — Bragg diffraction, Python library.
  • crysfml — Bragg diffraction, Fortran library with Python bindings.
  • pdffit2 — Total scattering (Pair Distribution Function), Python library.
  • easydiffraction — extra corrections around the engine (e.g. background, scale).

How to read this page

Each capability is tracked across the three ways to use EasyDiffraction:

  • LIB — Python library
  • CLI — command-line interface
  • APP — graphical application

The status icons:

  • ✅ Done
  • ☑ Partially done — available with at least one engine/interface
  • 🚧 Work in progress
  • 📅 Planned (no priority yet) · 5/5 highest · 4/5 high · 3/5 medium · 2/5 low · 1/5 lowest
  • Not available / not applicable — the engine/interface does not provide this
  • Unknown — support not yet confirmed for this engine/interface
How the columns are scored

The LIB column aggregates the per-engine lines in the Feature cell (the engines are the library backends): ✅ when every relevant engine is done (engines that do not apply are marked ), and ☑ when at least one engine is done but others are in progress or planned. The CLI and APP columns show whether the feature is available in those two interfaces.

Using the command-line interface

The CLI runs the refinement workflow — fit, display, undo. Models, parameters, constraints, and report options are set by editing the project text files (.edi/CIF) in your own editor, rather than through dedicated CLI commands. A ✅ in the CLI column means the capability is reachable through this edit-then-run workflow.

Icons inside the Feature cell

Each line in the Feature cell carries its own icon:

  • The engine lines show per-engine status, e.g. ✅ cryspy (done) or 📅 crysfml (planned). A backend keyword is shown in quotes (e.g. cryspy "Gauss").
  • cross-references the equivalent FullProf .pcr entry, to help users coming from FullProf.
  • links to the Verification page where the calculation is cross-checked against an independent reference.
Epics shown as single rows

Large areas still on the roadmap — magnetic structures, polarized neutron diffraction, 2D Rietveld, incommensurate structures — are listed as one top-level row each. They are epics that will be broken into detailed rows once work starts. Already-implemented areas are shown in full detail.

1. Structure Model

1.1. Crystal Structure

Space Group

Feature LIB CLI APP
Hermann-Mauguin space-group symbol
- ✅ cryspy
- ✅ crysfml
- ✅ pdffit2		 ✅ ✅ ✅
Space group IT number
- 📅 easydiffraction		 📅 📅 📅
IT coordinate system code
- ✅ cryspy
- crysfml
- pdffit2
- FullProf ":1" (origin choice)		 ☑ ☑ ✅

Cell

Feature LIB CLI APP
Lengths a, b, c
- ✅ cryspy
- ✅ crysfml
- ✅ pdffit2		 ✅ ✅ ✅
Angles α, β, γ
- ✅ cryspy
- ✅ crysfml
- ✅ pdffit2		 ✅ ✅ ✅

Atom Sites

Feature LIB CLI APP
X-ray scattering factors (tabulated)
- ✅ cryspy
- ✅ crysfml
- ✅ pdffit2		 ✅ ✅ ✅
Neutron scattering lengths for natural elements (tabulated)
- ✅ cryspy
- ✅ crysfml
- ✅ pdffit2		 ✅ ✅ ✅
Isotope-specific neutron scattering length (e.g. ¹¹B, ²H)
- ✅ cryspy
- crysfml
- pdffit2		 ☑ ☑ 📅
Custom neutron scattering length
- cryspy
- crysfml
- pdffit2
- FullProf "Nsc (user-defined scattering)"		 📅 📅 📅
Fractional coordinates x, y, z
- ✅ cryspy
- ✅ crysfml
- ✅ pdffit2		 ✅ ✅ ✅
Occupancy
- ✅ cryspy
- ✅ crysfml
- ✅ pdffit2		 ✅ ✅ ✅
Symmetry wyckoff_letter
- ✅ easydiffraction		 ✅ ✅ ✅

Atomic Displacement (ADP)

Feature LIB CLI APP
Isotropic Biso
- ✅ cryspy
- ✅ crysfml
- ✅ pdffit2
- ✅ easydiffraction (B/U/β conversion)		 ✅ ✅ 📅
Isotropic Uiso
- ✅ cryspy
- ✅ crysfml
- ✅ pdffit2
- ✅ easydiffraction (B/U/β conversion)		 ✅ ✅ ✅
Anisotropic Bani (B11…B23)
- ✅ cryspy
- crysfml
- ✅ pdffit2
- ✅ easydiffraction (B/U/β conversion)		 ☑ ☑ 📅
Anisotropic Uani (U11…U23)
- ✅ cryspy
- crysfml
- ✅ pdffit2
- ✅ easydiffraction (B/U/β conversion)		 ☑ ☑ 📅
Anisotropic β (β11…β23)
- ✅ cryspy
- crysfml
- pdffit2
- ✅ easydiffraction (B/U/β conversion)		 ☑ ☑ 📅

Note

CrysFML refines only isotropic ADPs today; for anisotropic atoms it uses the isotropic-equivalent B, so true anisotropic refinement in crysfml is unconfirmed ( on the anisotropic rows). EasyDiffraction stores ADPs type-neutrally and converts between B, U, and β for each engine, so the easydiffraction line marks that conversion. pdffit2 works in U; its β support is likewise unconfirmed.

1.2. Magnetic Structure

Magnetic structure refinement is an epic (one row per area for now).

Feature LIB CLI APP
Irreducible representations 📅 📅 📅
Magnetic Space Groups 📅 📅 📅
Symmetry-adapted modes 📅 📅 📅
Magnetic propagation vector (kx, ky, kz)
- FullProf "Nvk (propagation vectors)"		 📅 📅 📅
Magnetic moments (mx, my, mz)
- FullProf "Rx, Ry, Rz"		 📅 📅 📅
Local Susceptibility (𝜒11…𝜒23) 📅 📅 📅
Magnetic domains 📅 📅 📅

2. Experiment Model

Technique LIB CLI APP
2.1. Powder Diffraction ☑ ☑ ☑
2.2. Single-Crystal Diffraction ☑ ☑ ☑
2.3. Polarized Powder Diffraction — EPIC 📅 📅 📅
2.4. Polarized Single-Crystal Diffraction — EPIC 📅 📅 📅

2.1. Powder Diffraction

Common features

Linked Phases
Feature LIB CLI APP
Scale factor
- ✅ easydiffraction		 ✅ ✅ ✅
Excluded Regions
Feature LIB CLI APP
Multiple regions: start/end positions
- ✅ easydiffraction		 ✅ ✅ 📅

Standard Bragg diffraction

Fitting Methods
Feature LIB CLI APP
Rietveld refinement (full pattern)
- ✅ cryspy
- ✅ crysfml		 ✅ ✅ ✅
Le Bail refinement (profile matching)
- cryspy
- crysfml
- FullProf "Jbt=2 (profile matching)"		 📅 📅 📅
Background

Background curves are evaluated by EasyDiffraction and added to the calculated pattern; the engine is not involved.

Feature LIB CLI APP
Line segments type: position, intensity
- ✅ easydiffraction
- FullProf "Nba" (linear interpolation points)		 ✅ ✅ ✅
Chebyshev polynomial type: order, coefficient
- ✅ easydiffraction
- FullProf "Nba=0 (polynomial background)"		 ✅ ✅ 📅
Automatic background estimation: auto or arPLS, FABC, SNIP
- ✅ easydiffraction		 ✅ ✅ 📅
Preferred Orientation
Feature LIB CLI APP
March–Dollase: march_r, random fraction, hkl axis
- ✅ cryspy
- 🚧 crysfml
- FullProf "Nor=1", "Pref1/2, Pr1/2/3"		 ☑ ☑ 📅
Instrument — Constant Wavelength
Feature LIB CLI APP
Wavelength: λ
- ✅ cryspy
- ✅ crysfml
- FullProf "Lambda1"		 ✅ ✅ ✅
Second wavelength: λ₂, I₂/I₁ ratio
- ✅ easydiffraction (Kα₁/Kα₂ doublet; engine run twice)
- cryspy
- 🚧 crysfml
- FullProf "Lambda2, Ratio"		 ☑ ☑ 📅
2θ offset
- ✅ easydiffraction
- FullProf "Zero"		 ✅ ✅ ✅
Sample displacement and transparency corrections
- ✅ cryspy
- 📅 crysfml
- FullProf "SyCos, SySin"		 ☑ ☑ 📅
Absorption correction (cylinder, Hewat)
- ✅ easydiffraction
- FullProf "muR"		 ✅ ✅ 📅
X-ray Lorentz-polarization correction: polarization coefficient, monochromator 2θ
- ✅ cryspy
- ✅ easydiffraction (for crysfml)
- FullProf "Cthm, Rpolarz"		 ✅ ✅ 📅
Instrument — Time-of-Flight
Feature LIB CLI APP
2θ bank
- ✅ cryspy
- 📅 crysfml
- FullProf "2-theta bank"		 ☑ ☑ ✅
d → TOF conversion: offset, linear, quadratic (reciprocal defined but not yet wired)
- ✅ cryspy
- 📅 crysfml
- FullProf "Zero, Dtt1, Dtt2, Dtt_1overd"		 ☑ ☑ ✅

Note

CrysFML's TOF branch is not yet functional (it parses TOF input but returns zero intensities), so TOF profiles and TOF instrument parameters are cryspy-only today; crysfml is marked 📅.

Peak Profile — Common (CWL + TOF)

Applies to every Bragg peak profile below, in both constant-wavelength and time-of-flight modes.

Feature LIB CLI APP
Peak-range cutoff (speed vs accuracy)
cutoff in FWHMs; 0 = full range
- ✅ cryspy
- 📅 crysfml
- FullProf "WDT"		 ☑ ☑ 📅
Peak Profile — Constant Wavelength
Feature LIB CLI APP
Thompson-Cox-Hastings pseudo-Voigt
Gaussian broadening U, V, W
Lorentzian broadening X, Y
- ✅ cryspy
- ✅ crysfml
- FullProf "Npr=7"		 ✅ ✅ ✅
Thompson-Cox-Hastings pseudo-Voigt + Bérar-Baldinozzi asymmetry
Gaussian broadening U, V, W
Lorentzian broadening X, Y
Bérar-Baldinozzi asymmetry a₀, b₀, a₁, b₁
- ✅ cryspy
- crysfml
- FullProf "Npr=7" + "Asy1-4"		 ✅ ✅ ✅
Thompson-Cox-Hastings pseudo-Voigt + Finger-Cox-Jephcoat asymmetry
Gaussian broadening U, V, W
Lorentzian broadening X, Y
Finger-Cox-Jephcoat asymmetry 1, 2
- cryspy
- ✅ crysfml
- FullProf "Npr=7" + "S_L/D_L"		 ✅ ✅ 📅
Peak Profile — Time-of-Flight
Feature LIB CLI APP
Pseudo-Voigt (non-convoluted)
Gaussian σ₀, σ₁, σ₂, size_g, strain_g
Lorentzian broadening γ₀, γ₁, γ₂, size_l, strain_l
- ✅ cryspy "non-conv-pseudo-Voigt"
- 📅 crysfml
- FullProf "Npr=7" (TOF)		 ☑ ☑ 📅
Jorgensen (back-to-back exp ⊗ Gaussian)
Gaussian broadening σ₀, σ₁, σ₂, size_g, strain_g
Asymmetry rise α₀, α₁; decay β₀, β₁
- ✅ cryspy "Gauss"
- 📅 crysfml
- FullProf "Npr=9" (Gaussian limit)		 ☑ ☑ ✅
Jorgensen-Von Dreele (back-to-back exp ⊗ pseudo-Voigt)
Gaussian broadening σ₀, σ₁, σ₂, size_g, strain_g
Lorentzian broadening γ₀, γ₁, γ₂, size_l, strain_l
Asymmetry rise α₀, α₁; decay β₀, β₁
- ✅ cryspy "pseudo-Voigt" (size/strain )
- 📅 crysfml
- FullProf "Npr=9"; "Iso-GSize, Iso-GStrain, Iso-LorSize, Iso-LorStrain"		 ☑ ☑ ✅
Double back-to-back exp ⊗ pseudo-Voigt
Gaussian broadening σ₀, σ₁, σ₂, size_g, strain_g
Lorentzian broadening γ₀, γ₁, γ₂, size_l, strain_l
Asymmetry rise α₁, α₂; fast decay β₀₀, β₀₁; slow decay β₁₀; switching r₀₁, r₀₂, r₀₃
- ✅ cryspy "type0m"
- Z-Rietveld "type0m" (no direct FullProf Npr; cf. Npr=10)		 ✅ ✅ 📅
Ikeda-Carpenter ⊗ pseudo-Voigt
Gaussian broadening σ₀, σ₁, σ₂
Lorentzian broadening γ₀, γ₁, γ₂
Moderator pulse α₀, α₁, β₀, κ
- 📅 cryspy
- 📅 crysfml
- FullProf "Npr=13"		 📅 📅 📅

Total Scattering (Pair Distribution Function)

Feature LIB CLI APP
Gaussian-damped sinc termination
cutoff Qmax, broadening Qbroad, sharpening δ₁, δ₂,
damping Qdamp, particle diameter spdiameter
- ✅ pdffit2 		✅ ✅ 📅

2.2. Single Crystal Diffraction

Extinction

CrysPy's extinction is an analytical Becker-Coppens spherical model with a Gaussian or Lorentzian mosaicity distribution.

Feature LIB CLI APP
Isotropic Becker-Coppens, Gaussian model: radius, mosaicity
- ✅ cryspy 		✅ ✅ ✅
Isotropic Becker-Coppens, Lorentzian model: radius, mosaicity
- ✅ cryspy		 ✅ ✅ ✅
Anisotropic extinction correction
- cryspy
- crysfml
- FullProf "Ext-Model=4 (anisotropic)"		 📅 📅 📅

Structural twinning

Feature LIB CLI APP
Structural twinning
- 📅 cryspy
- crysfml		 📅 📅 📅

Instrument — Constant Wavelength

Feature LIB CLI APP
Wavelength
- ✅ cryspy
- 📅 crysfml
- FullProf "Lambda1"		 ☑ ☑ ✅
Half wavelength (λ/2)
- 📅 cryspy
- 📅 crysfml
- FullProf "x-Lambda/2"		 📅 📅 📅

Instrument — Time-of-Flight

Feature LIB CLI APP
Individual wavelength per reflection
- ✅ cryspy
- crysfml		 ☑ ☑ 📅

2.3. Polarized Powder Diffraction

Polarized-neutron powder diffraction is an epic. Planned: flipping-ratio method.

2.4. Polarized Single-Crystal Diffraction

Polarized-neutron single-crystal diffraction is an epic. Planned: flipping-ratio method, XYZ polarisation analysis, spherical neutron polarimetry.

3. Multi-Dataset Support

Feature LIB CLI APP
Multiple structural data blocks ✅ ✅ ✅
Multiple experimental data blocks ✅ ✅ 📅

4. Analysis (Fitting)

4.1. Calculation Modes

Feature LIB CLI APP
Calculate diffraction pattern (for fitting/comparison)
- ✅ cryspy
- ✅ crysfml
- ✅ pdffit2		 ✅ ✅ ✅
Calculate diffraction pattern (simple view, no data)
- ✅ cryspy
- ✅ crysfml
- 📅 pdffit2		 ☑ ☑ ☑
Calculate structure factors
- ✅ cryspy
- 📅 crysfml		 ☑ ☑ ✅

4.2. Refinement Algorithms (numerical derivatives)

Minimizers are EasyDiffraction's optimizers and run with any engine.

Feature LIB CLI APP
Levenberg–Marquardt — LMFIT (leastsq) minimizer ✅ ✅ ✅
Trust Region Reflective — LMFIT (least_squares) minimizer ✅ ✅ ✅
Levenberg–Marquardt — BUMPS (LM) minimizer ✅ ✅ 📅
Nelder-Mead — BUMPS (AMOEBA) minimizer ✅ ✅ 📅
Differential evolution — BUMPS (DE) minimizer ✅ ✅ 📅
Derivative-free minimization — DFO-LS minimizer ✅ ✅ ✅

4.3. Bayesian Analysis (Markov Chain Monte Carlo sampling)

Feature LIB CLI APP
DiffeRential Evolution Adaptive Metropolis — BUMPS (DREAM) minimizer ✅ ✅ 📅
Affine-invariant ensemble sampling — EMCEE minimizer ✅ ✅ 📅
Resume sampling — BUMPS (DREAM) minimizer ✅ ✅ 📅
Resume sampling — EMCEE minimizer ✅ ✅ 📅

4.4. Fit Strategies

Feature LIB CLI APP
Single fit of one experiment to one or more structures ✅ ✅ ✅
Sequential fit of experimental data blocks ✅ ✅ 📅
Joint fit within the same calculation engine ✅ ✅ 📅
Joint fit using different engines (e.g. CrysPy + Pdffit2) ✅ ✅ 📅
Custom weighting for joint fit: weight per dataset ✅ ✅ 📅

4.5. Live Fitting

Feature LIB CLI APP
Live fitting during real-time data acquisition 📅 📅 📅

5. Refinement Execution

Feature LIB CLI APP
GUI-driven refinement workflow ✅
Command-line refinement execution ✅
Scripted refinement workflow ✅
Parameter modification ✅ ✅ ✅
Load individual structure or experiment files ✅ ✅ ✅
Project-based refinement ✅ ✅ ✅
Sequential refinement ✅ ✅ 📅
Save refinement results to project ✅ ✅ ✅
Undo last fit ✅ ✅ 📅

6. Constraints

Feature LIB CLI APP
Automatic symmetry constraints ✅ ✅ ☑
User-defined constraints
e.g. "biso_Ba = biso_La", "occ_Ba = 1 - occ_La"		 ✅ ✅ 📅

7. Data Management

7.1. Project Files

Feature LIB CLI APP
Load full project from disk ✅ ✅ ✅
Save full project to disk ✅ ✅ ✅

7.2. Reports

Feature LIB CLI APP
Interactive HTML report (Plotly fit plots, Three.js 3D structures; offline option) ✅ ✅ 📅
LaTeX (TeX) report ✅ ✅ 📅
PDF report (compiled from the TeX bundle; requires a LaTeX engine) ✅ ✅ 📅
CIF report (IUCr-style) ✅ ✅ 📅

7.3. Data Loading

Feature LIB CLI APP
Add structure (to project) from CIF ✅ ✅ ✅
Add structure (to project) from edi ✅ ✅ ✅
Add experiment data (to project) from CIF ✅ ✅ ✅
Add experiment data (to project) from edi ✅ ✅ ✅
Add experiment data (to project) from ASCII ✅ ✅ ✅
Add experiment data (to project) from NeXus 📅 📅 📅

7.4. SciCat Integration

Feature LIB CLI APP
Load full project from SciCat 📅 📅 📅
Save full project to SciCat 📅 📅 📅

7.5. External Resources

Feature LIB CLI APP
List available tutorial Jupyter notebooks ✅ ✅
Download tutorial Jupyter notebooks ✅ ✅

8. Visualization

8.1. Structure

Crystal Structure

Feature LIB CLI APP
Visualize unit cell ✅ 📅 ☑
Visualize multiple unit cells 📅 📅 📅
Visualize atom sites as spheres ✅ 📅 ✅
Visualize atoms occupied same position ✅ 📅 📅
Visualize bonds ✅ 📅 📅
Visualize polyhedra 📅 📅 📅
Interactive mode: 3D rotation, zooming ✅ 📅 ✅

Magnetic Structure

Feature LIB CLI APP
Visualize magnetic moments 📅 📅 📅
Visualize magnetization densities 📅 📅 📅

8.2. Experiment

Powder Diffraction

Feature LIB CLI APP
Plot experimental curve ✅ ✅ ✅
Plot calculated curve ✅ ✅ ✅
Plot residual curve ✅ ✅ ✅
Plot Bragg peaks ✅ ✅ ✅
Interactive mode: zooming, panning ✅ ✅

Single Crystal Diffraction

Feature LIB CLI APP
Plot obs vs calc for reflections ✅ ✅ ✅
Interactive mode: zooming, panning ✅ ✅

8.3. Analysis

Feature LIB CLI APP
Live update of plots on parameter change with slider ✅
Live update of plots during refinement ✅
Live update of fit quality (change in χ²) — table/statusbar ✅ ✅ ✅
Live update of fit quality (change in χ²) — chart 📅 📅
Parameter evolution (sequential refinement) ✅ ✅ 📅
Correlation between parameters ✅ ✅ 📅
Posterior pair (corner) plot ✅ ✅ 📅
Posterior marginal distributions ✅ ✅ 📅
Posterior predictive bands ✅ ✅ 📅

9. User documentation

Feature LIB CLI APP
New unified documentation structure ✅ ✅ 📅
Introduction ✅ ✅ ☑
Features ✅ ✅ 📅
Installation and setup guide ✅ ✅ ☑
User guide ✅ ✅ ☑
Tutorials ✅ 📅 📅
Verification ✅ ✅ 📅
Command-line interface ✅
Quick Reference ✅ ✅ 📅
API reference ✅

10. Backlog

Items not yet scheduled or detailed. Several are epics (large areas that will be split into detailed rows once work begins).

Feature LIB CLI APP
Incommensurate structures — EPIC 📅 📅 📅
2D Rietveld refinement — EPIC 📅 📅 📅
Chatbot for natural-language requests during analysis 📅
Refinement using analytical derivatives 📅 📅 📅
Global optimization algorithms (e.g. simulated annealing) 📅 📅 📅
Built-in refinement strategies for common workflows 📅 📅 📅
Restraints (soft constraints, e.g. bond lengths, angles) 📅 📅 📅
Search and download structure from Crystallography Open Database (COD) 📅 📅
Read instrument resolution parameters from file
- FullProf "Irf" (.irf resolution file)		 📅 📅 📅
Set free parameters by category (e.g. all atomic positions, all ADPs) 📅 📅 📅