To calculate solubility, we measure the average number of molecules within the membrane over a 400ns period. It is important to consider that there are two membrane-gas interfaces in this setup, and the adsorption behavior at these interfaces may differ from that in the bulk of the membrane. Consequently, for a 6 nm thick membrane, we focus on the central 4nm region to ensure that the calculations reflect the bulk properties rather than the interfacial effects. This approach helps to provide a more accurate assessment of the solubility within the membrane.