For the same arguments given in the dimer example, a water molecule accepting more HBs from neighbouring waters is a better HB donor than one accepting fewer HBs, therefore DDDA motifs result in stronger BEs than DDSA. Likewise, A+DDDA represents a more Examining the most stable complex of each water cluster with each of the organic probes shows that the profile of benchmark binding energies (Figure ) has an irregular trend with increasing n in (H 2 O) n without appearing to reach an asymptote by n --10. To explain this trend in the curves, we noted that the water cluster displaying the strongest HB interactions belongs to the water heptamer -this it is the largest water cluster presenting book-like geometries, which allow for A+DDDA type interactions. Of the 11 heptamer structures we obtained from the literature, 6 are open structures (i.e. they do not form cages or prisms) which allow for A type interactions in addition to DDDA interactions. In contrast, the These findings suggest to us that the magnitude of the BEs obtained with the heptamer are likely to be quite close to the maximum HB strengths between the probes and water clusters.