Löwdin tends to include a broader spatial region in each fragment due to its more delocalized nature, whereas IAO+PAO focuses on retaining only the orbitals that are strictly necessary for describing the local chemistry, resulting in more compact fragments. The water clusters analyzed contain 6, 7, and 8 water molecules, with 4 isomers considered for each cluster. The structures and names of the isomers are shown in Figures . Table presents the relative energies of the four isomers, calculated relative to the first isomer, in kcal/mol. The methods compared include all-electron CCSD(T), SCF-DF-DMET-CCSD(T) using Löwdin-generated fragments, and SCF-DF-DMET-CCSD(T) using IAO+PAO-generated fragments. Table shows the percentage of correlation energy recovered, using all-electron energy as a reference, for the different isomers.