The DFT calculations in Part 1 and 2 employed molecularly optimised (MOLOPT) basis sets from the work of VandeVondele and Hutter. Both double-zeta short-range basis sets (DZVP-MOLOPT-SR, labelled "DZVP-SR" for brevity in the following) and triple-zeta basis sets (TZVP-MOLOPT) were used, as discussed in the Results section. Preliminary tests showed that the use of larger triple-zeta basis sets (TZV2P-MOLOPT, TZV2PX-MOLOPT) resulted in only marginal changes in the adsorption energies that usually remained below 3%. Only the Γ point was used to sample the first Brillouin zone. The plane wave energy cutoff was set to 600 Ry, as preliminary calculations indicated that this value gave well converged adsorption energies (use of an energy cutoff of 800 Ry typically resulted in changes by less than 2%). Goedeker-Teter-Hutter pseudo-potentials developed by Krack were used to represent the core electrons. Structure optimisations were considered converged when the following convergence criteria were simultaneously met: Maximal residual force below 2.5•10 -6 Ha bohr -1 and maximal displacement below 5•10 -5 bohr. For calculations on isolated contaminant molecules, the periodicity was switched off (keyword: PERIODIC: NONE). A wavelet solver was used to solve Poisson's equation for these non-periodic systems. In calculations with non-local vdW-DF functionals, it was found that a Fast Fourier Transform (FFT) cutoff of 400 Ry gave converged results.