Both in terms of adsorption energies and equilibrium structures, fairly similar results were obtained for zeolite models having vastly different Si/Al ratios, but identical proton arrangements in the 12MR where 5-FU is adsorbed. This indicates that models containing only a few framework protons can be useful to represent specific local environments. However, it should be kept in mind that the presence of 2 or 3 protons in the same 12MR at Si/Al ratios of 95 and 63, respectively, appears extremely improbable when assuming a more or less statistic distribution. Thus, these structures should be seen as representatives of possible local arrangements at lower Si/Al ratios, rather than being realistic models. An additional simplification made in the present study was the assumption that the framework protons are always bonded to O1 oxygen atoms, neglecting the possibility to occupy different sites at finite temperature.