Help with Simulating Henry's Coefficient of Methane and CO₂ in Water Using RASPA

[jemilu]

Dear RASPA Community,

I am a beginner with RASPA and am working on simulating the solubilities of methane and carbon dioxide in water using Monte Carlo methods. Following the RASPA manual, I have set up my simulation as follows:

    Water Equilibration:
    I used molecular dynamics to equilibrate water molecules at 298 K and 1 atm.
    Monte Carlo Simulation:
    Methane and carbon dioxide insertion/deletion was performed using the input below:

SimulationType               MonteCarlo
NumberOfCycles               50000
NumberOfInitializationCycles 5000
PrintEvery                   1000
RestartFile                  yes

ChargeMethod                 Ewald

Box                          0
BoxLengths                   25.10759 25.10759 25.10759
BoxAngles                    90 90 90
ExternalTemperature          298
ExternalPressure             101325
ComputeMoleculeProperties    yes
ComputeMolecularPressure     yes
ComputeMSD                   yes
PrintMSDEvery                5000
Movies                       yes
WriteMoviesEvery             100
ComputeRDF                   yes
writerdfevery                1000

Component 0 MoleculeName             water
            TranslationProbability   0.5
            RotationProbability      0.5
            ReinsertionProbability   0.5
            VolumeChangeProbability  0.1
            CreateNumberOfMolecules  0

Component 1 MoleculeName             methane
            TranslationProbability   0.5
            RotationProbability      0.5
            CFSwapLambdaProbability  1.0
            CreateNumberOfMolecules  0
            WidomProbability         1.0


I included WidomProbability to compute Henry's coefficient, as described in the manual. However, the Henry's coefficient does not appear in the output. I suspect this might be due to water being a high-density liquid rather than a porous material like a MOF.

My main question is:
How can I calculate the Henry's coefficient for methane and carbon dioxide in water at varying pressures using RASPA?

This coefficient is essential for applying Henry's law to determine partial pressures for my research.

Thank you in advance for your guidance.

Best regards,
Jemilu Omeje Audu