We optimize the LJ 𝑅 𝑚𝑖𝑛∕2 and 𝜖 for 6 LJ types, which are described in Table . We also note that several LJ types are exercised by molecules in the training set, but are not optimized, due to either having very specific chemical contexts that are not exercised widely enough to optimize, or, in the case of the [#1:1]-[#8] (hydroxyl hydrogen) parameter, because the 𝜖 has been set to an arbitrary small non-zero value to avoid unphysical effects .