Given that the plane wave methods used to calculate the energy of the ZIF-zni crystal structure are very different to the molecular methods used to calculate the GFN2-xTB/ωB97X energies of the clusters, it could be reasonable to think that these two types of energies cannot be compared. For that reason, we also plotted the energies of the neutral clusters, now obtained with the same meta-GGA plane wave calculations. We see that the energies of the clusters calculated with both types of calculations are very similar, so that we can indeed use the bulk energy as a reference energy towards which the cluster energies must converge, with some confidence. The results, shown in Figure , indicate that the clusters we are studying are still very far away from achieving the stability of the most stable bulk structure (that of ZIF-zni, with a free energy of -6.18 eV). In Table we have listed the energies of the other calculated periodic structures. For that reason, our results suggest that clusters with bulk-like geometries are not the most stable at the cluster size considered here, so that further growth must take place before surface effects have a lower impact on the cluster structures and allow classical crystal growth to proceed. Interestingly, in Figure , we observe that the lines calculated by fitting the series of energies obtained for each value of z and for varying values of l, converge to a formation energy of ∼ -7.5 eV, for both l = Im and l = mIm, although there is no clear physical interpretation of this fact.