chemical potential in GCMC

Hello Loukas,

One way to get a chemical potential is to run several simulations of the system in the gas phase until you get a reasonable pressure. If you have available experimental results, you could compare the pressure versus density relationship obtained through these simulations versus experiment. Then, if you're interested in computing adsorption isotherms in a porous material, you could use the chemical potential obtained from the pure substance simulation as the chemical potential in the adsorption calculation.

Please let us know if this works.

If you are simulating a mixture, then the chemical potentials you input are that of the mixture. So for example, let's say you want to simulate a gas mixture in contact with a zeolite at a given condition. You need to do a pre-simulation of the gas phase and relate the pressure-composition-temperature behavior of the gas phase to the chemical potentials for each species. Then when you use these chemical potentials in the GCMC simulation, it will model the gas phase in contact with the solid. Under low pressure, high temperature conditions, the gas phase will act nearly ideal and you can probably get away with using pure gas chemical potentials, but technically you need to relate the chemical potentials to the mixture properties.