Again, for each cluster size different structural isomers are considered. The structures have been taken from Ref. . For applying the MBE, these clusters are partitioned into one H 3 O + cation and N water molecules. We note that some isomers contain a Zundel ion, H 5 O + 2 , as a substructure, which is nevertheless partitioned into an H 3 O + cation and a water molecule. Previously, it was found that with an isolated eb-MBE, three-body contributions amount to up to 40 kJ/mol, four-body contributions can be as large as 5.5 kJ/mol, whereas five-body contributions become negligible .