## Running BornAgain through the GUI

BornAgain comes with a graphical user interface (GUI). Based on the library Qt6, it has a native look and feel under all three supported operating systems. It allows users to view experimental and simulated data, to set up and parameterize physical models, and to run fits.

A graphical sample editor allows users to set up multilayer models. Model components like embedded particles or inter-particle correlation functions are represented by groupboxes with editable fields. Simultaneously, the real-space structure of the sample, or any of its components, can be shown in an interactive 3D visualization. This provides users with feedback as to whether the model, constructed in abstract terms in the sample editor, corresponds to their actual intentions. Moreover, a real-space representation can be helpful when communicating scientific results to audiences that are not familiar with the reciprocal-space thinking of scattering practitioners.

All model parameters can also be seen and set from a tree view. To explore their impact upon the simulated GISAS pattern, it is possible to modify parameter values with sliders. Unless the model is excessively computing intensive, the outcome view is kept up to date without noticeable delay. All model and parameter choices made in an interactive GUI session can be stored in XML and can be reloaded in another GUI session. They can also be stored as a Python script, which can then be run from the command line, independently of the GUI. This helps users who reach the limits of GUI functionality to get started with using BornAgain from Python, since it is much easier to edit a given script than to write one from scratch.

Until release 20.0, there was no mechanism to ensure backward compatibity. BornAgain 20 is not able to read GUI project files from older software versions.

- Quick Start
- GUI overview
- Fitting in the GUI

- Introduction
  - Functionality overview
  - Architectural overview

- Install or build
  - Install Python
    - Python on Linux
    - Python on Windows
    - Python on Mac
    - Python modules
  - Install BornAgain
    - Linux
    - Windows
    - MacOS
    - Development snapshot
  - Build BornAgain
    - Unix
      - Install third-party software
      - Get the source
      - Build and install BornAgain
      - Run a first simulation
    - Windows

- Graphical user interface
  - Quick Start
  - GUI overview
  - Fitting in the GUI

- Python scripting
  - Run a script
  - Understand the syntax
  - Fitting
  - Upgrading

- Reference
  - Simulation model
    - Simulation classes
      - Specular
        - Example
      - Scattering
        - Examples
          - GISAS
          - without DWBA terms
          - with specular peak
          - SAS
          - Polarized SANS
          - Monte-Carlo
      - Off-specular
        - Off-specular
      - Depth probe
        - Examples
          - Thin film
          - Transmitted modulus
          - Resonator
    - Common settings
      - Background
      - Options
        - Monte-Carlo
        - # threads
        - Average materials
        - Include specular
      - Progress monitor
  - Instrument model
    - Beam
      - Footprint
      - Beam divergence
    - Scan
      - TOF reflectometry
      - TOF resolution
      - Beam Angular Spread
      - Beam Wavelength Spread
    - Detectors
      - SphericalDetector
      - 2d detector resolution
      - Offspec detector
    - Neutron polarization
      - Spin asymmetry example
    - Examples
      - 2D detector resolution
      - Neutron polarization
        - Magnetic layer
        - Ditto, realistic instrument
        - Polarized scattering
  - Sample model
    - Materials
      - Magnetization
    - Sample
      - Layer
      - LayerStack
      - Layout
    - Roughness
      - Interface model
      - Transient
      - Cross-correlation
      - Examples
        - GISAS
        - Reflectivity
    - Particles
      - Form factor
        - Hard particles
          - Bipyramid4
          - Box
          - CantellatedCube
          - Cone
          - Cylinder
          - Dodecahedron
          - EllipsoidalCylinder
          - HemiEllipsoid
          - HorizontalCylinder
          - Icosahedron
          - PlatonicOctahedron
          - PlatonicTetrahedron
          - Prism3
          - Prism6
          - Pyramid2
          - Pyramid3
          - Pyramid4
          - Pyramid6
          - Sphere
          - SphericalSegment
          - Spheroid
          - SpheroidalSegment
          - TruncatedCube
        - Ripples
          - Bar ripple
          - Cosine ripple
          - Sawtooth ripple
        - Soft particles
          - FuzzySphere
          - Gauss
        - Custom formfactor
      - Composite particles
        - Core and shell
        - Compound particle
        - Mesocrystal
      - Examples
        - Compound particle
        - Core and shell
        - Crossing an interface
        - Mesocrystal
        - Rotation example
        - Dense cylinders
        - Dense hemispheres
        - Uncorrelated mixture
        - Polydispersity
    - Particle assemblies
      - Grating
        - 1D lattice
        - Cosine ripples in a lattice
        - Triangular ripples in a lattice
      - 2D lattice
        - Square lattice
        - Lattice orientation distribution
        - Finite square lattice
        - Lattice with basis
        - Multi-layer lattice
        - Position variance
      - Radial paracrystal
      - 2D paracrystal
      - Others
        - Size-distribution model: decoupling approximation
        - Size-distribution model: local monodisperse approximation
        - Size-distribution model: size-spacing coupling approximation
  - Model modifiers
    - Rotation
    - Distributions
  - Data types
    - Class Datafield
      - Export
      - Find intensity peaks
    - SLD profile
      - SLD profile with rough interfaces
      - SLD profile with a sliced particle layer
  - Plotting
    - Functions
    - Configuration
    - Heat map
    - LaTeX markup
    - Export
    - Plot axes in different units
  - Fitting
    - Data import
      - TIFF
    - Minimizer settings
    - Multiple datasets
    - Examples
      - Fitting with masks
      - Custom objective function
      - Fitting along slices
      - GISAS 2D fits
      - Experiment at GALAXI
      - Find background
      - Minimizer settings
      - Bayesian Sampling
      - Consecutive fitting
      - Considering uncertainties
      - External minimizer
      - External minimizer: plotting
      - Simultaneous fit of two datasets
      - Spin asymmetry fit example
      - Reflectometry: Fit Pt layer
      - Reflectometry: Fit honeycomb

- Literature
  - Babonneau2010
  - Babonneau2013
  - Croset2021
  - Lazzari2002
  - Lazzari2006
  - Pospelov2020
  - Renaud2009
  - Sears1992
  - Wuttke2021

- How to
  - Get announcements
  - Solve known problems
    - Set Python environmental variables under Windows
  - Request help or report bugs
  - Cite BornAgain

- Developers' corner
  - Configure
    - Build
    - Pyenv
  - Develop
    - Manual checks
    - Debug
    - Webdoc
    - Code analyses
  - Release
    - Manual GUI test