For comparison, the MR-CIS minimum standard deviation δ min ∆E for ethylene was found to be 6 × 10 -4 eV, which is consistent with the level of convergence employed in the calculation of the electronic energies. A major shift in interpretation resulting from treating the local energetic variations in DFT/MRCI(2) as noise is the role of the single point calculations in the construction of surrogate PESs. It is no longer taken as the ground truth and is only meaningful within an interval governed by the learned noise. A consequence of this is that the degeneracy may not exist simultaneously in the DFT/MRCI(2) PESs and the GPR surrogate, and if it does, it may not correspond to the same set of geometries unless the noise approaches zero.