Upon comparison of the PA -clusters with literature, we see that both the (PA -) 1 (w) 1 and (PA -) 1 (w) 2 clusters are consistent with the clusters obtained by Petersen-Sonn et al. obtained at CAM-B3LYP/aug-cc-pVTZ level of theory and the clusters obtained by Shemesh et al. 109 at MP2/cc-pVDZ level of theory. As for the PA clusters examined previously, we observe discrepancies between our (PA -) 1 (w) 3-5 cluster geometries and literature geometries due to the dispersed water structure in these and as the water structure in our geometries are well-ordered and mainly located at the carboxylate terminus of PA -.