Such calculations 51 were basically at the limit of feasibility for hexamers. Since these FFs were trained peforce on small clusters, i.e., the dimer and trimer, the CCSD(T) calculations were feasible. It should be noted that both WHBB and MB-pol made use of polarizable FFs (TTM3 for WHBB and TTM4 for MB-pol) to account approximately for 4-and higher-body interactions. Numerous tests of the accuracy of MB-pol by Reddy et al have shown that this potential is robust for many applications. In particular for the eight hexamer isomers, a mean absolute error of 0.53 kcal/mol was reported. (Also, see Table .) Errors are larger using WHBB, however, both potentials obtained the correct energy ordering of the isomers, with the prism being the lowest energy isomer in electronic energy. In 2022, we reported q-AQUA which is a strict machine-learned, CCSD(T)-based potential including 4-b interactions. The MAE for these hexamer isomers is 0.25 kcal/mol, which is roughly half the MB-pol MAE. As shown here, q-AQUA-pol yields even more accurate electronic dissociation energies for the benchmark water hexamer isomers than q-AQUA.