The average loading of the MOF at a given pressure will be computed using grand-canonical Monte Carlo (GCMC) simulations with the RASPA code.
-
The RASPA code needs several input parameters, some of which you will need to figure out
parameters = ParameterData(dict={ "GeneralSettings": { "SimulationType" : "MonteCarlo", "NumberOfCycles" : 2000, "NumberOfInitializationCycles" : 2000, "PrintEvery" : 2000, "ChargeMethod" : "Ewald", "CutOff" : 12.0, "Forcefield" : "<string>", "EwaldPrecision" : 1e-6, "Framework" : 0, "UnitCells" : "<int> <int> <int>", "HeliumVoidFraction" : 0.0, "ExternalTemperature" : <float (Kelvin)>, "ExternalPressure" : <float (Pascal)>, }, "Component": [{ "MoleculeName" : "methane" "MoleculeDefinition" : "TraPPE", "TranslationProbability" : 0.5, "ReinsertionProbability" : 0.5, "SwapProbability" : 1.0, "CreateNumberOfMolecules" :0, }], })
-
Our simulations are performed under periodic boundary conditions. This means, we need to make our simulation cell large enough that a molecule will never interact with a two periodic copies of any of its neighbors. Given the cutoff radius of
$12$ Angstroms, how often do you need to replicate the unit cell of the material?Hint: The CIF files include information on the size of the unit cell.
-
To make things more interesting, we are going to use different force fields. Ask your instructor to give you a force field identifier.
-
-
You already performed a small GCMC calculation at 10 bar during the tutorial. Adapt the input file to your needs and run the calculation.
Hint: Once running, the calculation should finish within 5 minutes.