The RMSE for 30 BEBOP bond dissociation energies (8.20 kcal/mol), ∆ BD E 0 (Figure ), is comparable to the error in the 192 total atomization energies (8.42 kcal/mol), D 0 (Table Similarly, BEBOP had difficulty estimating the C --C BDE of ethylene (19.16 kcal/mol as shown in Figure ), as the bonding of each CH 2 fragment is underestimated by 7.00 kcal/mol and the C --C bonding of ethylene is overestimated by 5.00 kcal/mol (Table ). The failure of the BEBOP model to quantitatively describe the three-center two-electron bonds of diborane was noted previously. However, in most cases the BEBOP error is small enough to give us confidence in the BEBOP analysis. The BEBOP model, in general, generated better D 298 for the small alcohol molecules (Figure ) than all SQMs and some popular hybrid DFT methods. As shown in