Altogether, the results from this part show that use of different functionals results in pronounced differences in the magnitude of absolute adsorption energies. On the other hand, all functionals deliver very similar qualitative trends, with even the smallest squared correlation coefficient amounting to 0.84, and all except four 𝑅 2 values being larger than 0.90. the same molecule in one zeolite is affected, both in terms of adsorption energies and structures of the adsorption complexes. For this purpose, the investigation focussed on three organic contaminants, acetaminophen, ibuprofen, and triclosan, which differ considerably in terms of adsorption energies and conformational degrees of freedom. Figure shows the adsorption configurations of ACA@MOR that were included in the calculations (IBU@MOR and TCS@MOR configurations are shown in Table Unlike in Part 1, the structures of the adsorption complexes (and of free contaminant molecules) were optimised using TZVP-MOLOPT basis sets. For the Config1 cases, these adsorption energies can be directly compared to adsorption energies obtained from TZVP-MOLOPT single-point calculations on DZVP-MOLOPT-SR-optimised structures ("TZVP-MOLOPT/DZVP-SR"). These results are collected in the lower part of Table .1. The differences between TZVP-MOLOPT/TZVP-MOLOPT and TZVP-MOLOPT/DZVP-SR adsorption energies remain below 5 kJ mol -1 (in absolute terms), with the mean of absolute errors across the three contaminants not exceeding 2.3 kJ mol -1 , and remaining below 1.0 kJ mol -1 for 8 out of 13 functionals. As the total adsorption energies fall between -110 and -250 kJ mol -1 , such changes can be considered negligible.