>> Why quadratic rather than linear? > > Most physics-based scores are interaction energies between pairs of > particles. But not all of course, otherwise this would be a solved > problem already. Sure, but for what we do (namely, not gravitation), the number of pairs scales linearly with the number of atoms rather than quadratically (since we have terms with finite cutoffs and packing constraints).
> >> I don't see that being able to minimize the score cares about >> whether it >> increases as you add atoms > > That's not my point. The point is that physics-based forcefields are > balanced that way (and making up a new forcefield is a decades-long > endeavor). Rescaling all the terms is not likely to give correct > behavior. Rescaling a physics forcefield is harmless if all you are interesting in doing is preserving minima. That said, looking like existing physics force fields is a reasonable criteria. But that requires that the other terms scale with the number of atoms too (since all of the force fields have finite cutoffs).