Table . Calculated B3LYP/def2-TZVP interaction energetics, and their deviations from those calculated using the MMFF94 force-field. The noncovalent character of each interaction is also indicated (second column from the left). Statistical dispersion measures for virus-specific interactions are given in the bottom three rows Character (in order of significance) IE (kcal/mol) dMMFF94 First, let us compare our DFT results to those obtained using the MMFF94 force-field. Not quite surprisingly, exceptionally large deviations are observed for structures reflecting significant vdW contributions (note, in particular, those associated with the S-π stabilized 3-nCoV-b/c). Generally-smaller deviations are accordingly found for hydrophobic or "pure" hydrogen bonding interactions (which do not involve additional significant vdW contributions). It is important to note that for some structures, said deviations are similar in magnitude to the calculated interaction strength; this should indeed indicate that classical force fields of this sort might prove problematic in cases where just a few, well-defined noncovalent binding factors are considered. In the present such case, MMFF94 clearly fails to provide accurate energetics for many structures, and should thus not be relied upon for answering whether the particular interactions under consideration indicate higher ACE2 affinity for either SARS-CoV or 2019-nCoV. Electronic structure calculations capable of accurately describing noncovalent binding factors should therefore be used as a reliable source of information for such purposes.