Overall, a grid density of 2 Å -1 was selected because, at this value, the deviation with GCMC does not change by more than 5.5 % for the adsorption isotherms, requires a relatively short run time (median time of approximately 5 min), and experiences a low percentage of convergence failure. However, as this grid density may still display substantial numerical errors in the calculations of the enthalpies of adsorption, we set a criterion to detect these substantial numerical errors and re-run the whole isotherm with a grid density 0.5 Å -1 higher until a grid density of 4 Å -1 . At this grid density, the majority of the enthalpies of adsorption display extpected behavior, and the cases where it is not the case will be discussed in the manuscript (Sec. 4C). A criterion of a change of less than 10 kJ mol -1 of the enthalpy of adsorption between two consecutive pressures was implemented. and CO 2 , cDFT calculations differ a bit more, with respectively 5% and 16% of the Henry coefficients deviating by more than a factor of 2. These deviations should, however, be compared to the large range of values that Henry coefficients can display, as they span 4 orders of magnitude for N 2 and 6 orders of magnitude for CO 2 .