The Free Energy and Advanced Sampling Simulation Toolkit (FEASST) is a free, open-source, modular program to conduct molecular and particle-based simulations with flat-histogram Monte Carlo and molecular dynamics methods.

:doc:`/plugin/README` contains the list of features available. Some features include but are not limited to the following:

Simulation techniques

• Wang-Landau Monte Carlo
• Transition-matrix Monte Carlo
• Metropolis Monte Carlo
• Mayer-sampling Monte Carlo
• Configurational bias

Thermodynamic ensembles

• Microcanonical ensemble
• Canonical ensemble
• Grad canonical ensemble

Intermolecular interactions

• Hard spheres
• Lennard-Jones with Yukawa, LRC, force shift
• Patchy particles
• Charged interactions with the Ewald summation
• Cylindrical and slit pore confinement

Modern software

• Interface with C++ or as a Python module
• OpenMP parallelization
• Checkpointing to save and restart simulations

The following example Lennard-Jones Monte Carlo simulation may be found in :doc:`/tutorial/README`.

.. literalinclude:: tutorial/lj_brief.py
   :language: py

mkdir /path/to/feasst/build
cd /path/to/feasst/build
cmake -DUSE_SWIG=ON ..
make _feasst -j12
../py/run.sh ../py/test.py  # optional test

CMake attempts to find the python libraries. But you may want to specify them manually as follows:

cmake -DUSE_SWIG=ON -DSET_PYTHON_PATH=ON -DPYTHON_INCLUDE_PATH=/path/to/anaconda/include/python3.6m -DPYTHON_LIBRARIES=/path/to/anaconda/lib/libpython3.6m.so ..

It is recommended to use SWIG version 3 or 4 and not 2.

Python scrips are then run using /path/to/feasst/py/run.sh, which sets PYTHONPATH to /path/to/feasst/build. Alternatively, you could set the python path manually.

First, install the C++ library.

mkdir /path/to/feasst/build
cd /path/to/feasst/build
cmake ..
make install -j12
make test         # optional test

Then, compile the specific simulation you wish to run (e.g., tutorial).

cd /path/to/feasst/tutorial/
mkdir build; cd build
cmake ..
make
./lj_brief

CMake defaults to install in the build directory. But you can also specify the path as follows.

cmake -DCMAKE_INSTALL_PREFIX=/path/to/install/dir ..

Later when you build your executable you need to specify this path as follows:

cmake -DCMAKE_PREFIX_PATH=/path/to/install/dir ..