I am trying to compare the performance of few Quantum Chemistry property prediction ML models. I was looking at the following table from DOI: 10.1039/c7sc02664a
The problem is that it does not contain any units. A preprint (https://arxiv.org/pdf/1909.00259.pdf, Table 4) suggests that the energy units are Hartree. Among energy properties, HOMO, LUMO, and gap have reasonable values for Hartree unit. However, values reported for U0, U, H, and G look absurd. As a comparison, look at MAE for mean value of each property:
These are in [eV] units (1 Ha = 27.212 eV). In other words, for instance MPNN models MAE for U property is 55.78 [eV] vs 8.25 [eV] for the mean baseline. This does not make sense at all. [k cal/mol] sounds more reasonable but then why half the energies in one unit the other half in other unit, and then why there are no units in a paper published by Royal Society of Chemistry. Seems like I'm missing something. Thanks!