From Figure ) and (e, f), both CO2 and N2 show a greater degree of scattering between different FFs at lower pressures, and therefore poorer correlations. On the other hand, CO2 adsorption shows more scattering compared to N2. We note that CO2 simulated uptakes also seem more sensitive to the electrostatics than to the parameters of the LJ FF, as seen by the stronger correlations in Figure (a) compared to Figure (b); for N2, the opposite trend is observed. The observations above are easy to rationalise. It is known that the most favourable adsorption sites on a MOF will be occupied preferentially at lower pressures. The strength of the interactions between the adsorbing species and the framework is mediated by the partial charges assigned to framework atoms and the crossinteractions between the adsorbate and adsorbent (and hence the parameters of the LJ FF).