The ∼1000 CH 4 pure component isotherms generated in this work span a wide range of pressures (0.01 bar to 12.000 bar). To cover the full range, we ran NPT MC simulations at 25 • C and 25 different pressure points per adsorbate. For the departure function for the partial molar enthalpy to be accurate, it is crucial that the simulations successfully converge, especially at high pressures, where the density of the system is the highest. Figure compares the predicted density to the experimental density for CH 4 at the corresponding pressure points. It is evident from Figure , that for CH 4 , the computed and experimental density are in excellent agreement. Given that the simulations have successfully converged, we used Equation (2) to calculate the departure function for the partial molar enthalpy for CH 4 . Then we fitted the data with cubic splines. The fits are used to estimate the departure function at any interest pressure.