GCMC simulations are the primary means by which we study gas adsorption and separations in a given porous material.
For GCMC simulations, we use RASPA , which is commonly used when modeling porous materials.
RASPA does not ship with many of the widely used forcefields or molecular definition files. A collection of them can, instead, be found in our raspa_ase repository in the share folder. If you are looking to do GCMC simulations, you should read the "Molecular Simulations of Adsorption and Diffusion in Crystalline Nanoporous Materials" chapter by Dubbeldam and coworkers. For a more pedagogical treatment of all things molecular simulations, refer to "Understanding Molecular Simulation" by Frenkel and Smit.