CosmoRealGas

class CosmoRealGas(temperature, parameters=None)

Constructor for COSMO-RS gas phase. This can be used to calculate gas interactions in the COSMO-RS model.

Parameters:
chemicalPotential(species)

Calculate the gas phase chemical potential of the given species.

Parameters:

species (CosmoRealSpecies) – The species for which the chemical potential is calculated.

Returns:

The chemical potential.

Return type:

PhysicalQuantity of type energy

parameters()
Returns:

The parameters used for the COSMO-RS model.

Return type:

CosmoRSParameters

temperature()
Returns:

The temperature of the gas.

Return type:

PhysicalQuantity of type temperature

uniqueString()

Return a unique string representing the state of the object.

Usage Examples

Calculate the gas-phase pseudochemical potential of water with respect to the ideal screened state.

# Load the COSMO species
database = CosmoRSSpeciesDatabase()
water = database.exportSpecies('water')

# Create the gas.
gas = CosmoRealGas(
    298*Kelvin,
    parameters=CosmoRSParameters(),
)

# Calculate chemical potential of a methanol molecule in solvent water.
chemical_potential = gas.chemicalPotential(water)
nlprint(f'The chemical potential of gas-phase water with respect to ideal screened state is {chemical_potential}')

water_gas_example.py

Notes

The CosmoRealGas object calculates the pseudochemical potential of a gaseous species with respect to the ideal screened state surrounded by a perfect conductor. In COSMO-RS the gas phase chemical potenial is defined so that the vapor pressure \(p\) of a substance can be given as

\[p = p_0 \exp([\mu^{liq} - \mu^{gas}] / RT)\]

Here \(\mu\) is the chemical potential of the species and \(p_0\) is a reference pressure, defined to be 1 bar. For more information on the COSMO-RS formalism, including how the gas phase chemical potential is approximated, please refer to CosmoRSParameters. Note that the CosmoRealGas is instantiated only with a temperature and a parameter set. The pseudochemical potential of a CosmoRealSpecies is then determined by calling the chemicalPotential method which takes in the CosmoRealSpecies as an argument.