#BREIT: Balance Rate Equations for Ion Transportation

BREIT: Balance Equations for Atomic Reactions is an open source software written in C++, which solve analytically the equilibrium and non-equilibrium charge state distributions equations (c.f. HANS-DIETER BETZ Rev. Mod. Phys. 44, 465).

The differential equations (non-equilibrium case) are solved using the eigenvalues decomposition method, and the asymptotic limits (equilibrium case) are solved by matrix inversion. In addition, a Runge-Kutta method can be used for cross-check.

BREIT needs electron-loss and -capture cross-sections (as well as initial conditions) as inputs in order to solve the (non-equilibrium) Betz equations. Only charge q greater or equal than zero are supported. An INI-like format is used as input file. BREIT input file examples can be found here or there. JSON or XML input files will also be supported. Supported cross-section units are : "cm2", "1e-16 cm2", or "xb", where x is a SI prefix. The supported units of the penetration depth, required for the non-equilibrium solutions, are : "10 mg/cm2" or "xg/cm2" where x is a SI prefix.

Output equilibrium results are provided on demand in the form of :

• 1-electron approximation (txt file)
• no-approximation obtained from matrrix inversion (txt file)
• TODO : figures (pdf or root files)

Output non-equilibrium results are provided on demand in the form of :

• analytical formulae (txt file)
• table (txt file)
• figures (pdf or root files)

• --input-file path/to/inputfile (required)
• --output-directory path/to/output/dir (optional)
• --plot (optional)
• --save (optional)
• --save-equilibrium (optional)
• --save-analytic (optional)
• --save-approximation (optional)
• --save-table (optional)
• --save-fig-ne (optional)

• distance-to-equilibrium computation
• server
• numerical error from matrix operations + error propagation from input cross-sections
• multiple input files for ion-optics
• implement XML and JSON input-file parser
• refactor the alternative Runge-Kutta method
• more documentations

cmake >= 2.8.2

C++11 Compiler:

• GCC >= 4.6
• clang >= 3.2

Third party libraries:

• boost>=1.56 (required)
• Lapack>=3.5 (required for non-equilibrium solutions)
  • on linux use e.g. sudo apt-get install liblapack-dev
• Root 5.3x or Root >= 6.04(required for non-equilibrium solutions)

# "Bear_path_install" is used here as a directory name, but can be renamed as you want.
# Set the shell variable SIMPATH to the boost installation directory
export SIMPATH=~/boost_install
[setenv SIMPATH ~/boost_install]

cd ~/Bear_path_install
git clone https://github.com/NicolasWinckler/BREIT
cd BREIT
mkdir build
cd build
cmake ..
make

BREIT is distributed under the terms of the GNU Lesser General Public Licence version 3 (LGPL) version 3.