Finally, we note an interesting recent study by Paesani and co-workers in which a NN FF was "transfer-learned" using MB-pol as the source of data. The success in doing this was limited with respect to training on one property and transferability to other properties. This was especially extreme in the case of the many-body contributions to the water hexamer isomer energies. On the other hand if training was done on the n-body contributions to these energies, transferability to other properties was more successful, i.e., in agreement with MBpol was good. Given that MB-pol is a many-body based potential, this could perhaps be seen as somewhat circular. However, it may also indicate that an accurate treatment of many-body components of the water potential is indeed an effective way to train a force field. The excellent results for the many-body q-AQUA and q-AQUA-pol for the properties of water investigated to date support this latter possibility. stricted diffusion Monte Carlo calculations of the water dimer and trimer using q-AQUApol, demonstrate the robustness of the potential for these demanding quantum calculations.