This project consists of two packages - convergent beam simulation program (cbc) and experimental data processing package (cbc_dp)

Simulation for convergent beam diffration on a crystalline sample written in Python. Code is compatible with Python 2.X and 3.X.

For more information regarding the theory behind this see the article written by Prof. Henry Chapman.

It's a package called cbc, with which you can conduct a diffraction simulation. See usage examples: go to cbc package structure

Required dependencies:

• NumPy
• Numba
• SciPy
• matplotlib
• h5py

The package can perform convergent beam diffraction simulation of crystalline samples based on first Born approximation theory.

Available incoming beam models:

• Gaussian beam
• Bessel beam
• Lens beam with rectangular or circular aperture

Samples could be composed of different compound unit cells deffined by array of atom coordinates within the unit cell and corresponding B-factors. These data can be imported via PDB format file. Unit cells are arranged in a rectangular grid.

The library itself consists of two modules and an utility package:

• beam.py - a module with incoming beam classes
• lattice.py - a module with sample lattice classes
• wrapper.py - simulation calculation wrapper module
• utils - utility package:
  • utilfuncs.py - utility functions for convergent beam diffraction project
  • asf - atomic scattering factor calculation package:
    • load.py - a module, that loads atomic scattering factor fit coefficients
  • pdb - PDB data import package
    • readpdb.py - a module, that imports molecular structure .pdb files

Also there is a couple of usage examples:

• read.py - reading and ploting diffraction results
• diff_run.py - diffraction simulation example

• consider different crystall space groups

Experimental convergent diffraction data processing package. Data is acquired from PETRA P06 beamtime on June 13, 2019.

- Flatfield correction
- Median filtering
- Non maximum supression

- Progressive Probabilistic Hough line transform
- Line Segment Detector (LSD)

More information about Progressive Hough transform is written in this article and about Line Segment Detector in this article.

- Rotational diffraction pattern indexing
- Convergent beam indexer