Energies and optimized geometries with respect to QM reference are finally compared by relative energy difference (ddE), root-mean-square deviation of atomic positions (RMSD) and torsion fingerprint deviation (TFD), similar to our previous benchmark assessment. The ddE energies account for the energy difference (dE MM ) between each MM optimized conformer and the MM conformer with minimum energy, relative to the energy difference (dE QM ) between each corresponding QM optimized conformer and the QM conformer with minimum energy (compare-forcefields).