Both of the semi-empirical methods show similar performance, with GFN2-xTB having a slightly better correlation of the two. Both of the methods' rank correlations show more outliers than that of MACE. The mean correlation coefficients are lower than that of MACE, but similar for both of the semi-empirical methods -AM1 (0.76) and GFN2-xTB (0.80). The parity plot of GFN2-xTB shows a similarly offset correlation as that of AM1, where the BDEs are generally over-predicted by GFN2-xTB and under-predicted by AM1. Furthermore, the GFN2-xTB outliers are due to an oxygen-stabilised radical (see Figure ), however, it is unclear whether the outliers are an artefact of FGN2-xTB or are missed by the reference DFT.