The conversion of CO 2 into valuable products requires breaking at least one of its bonds. Hence, large values of ∆d C-O max can reflect high reactivity of the SAA surface sites. For this reason, ∆d C-O max is chosen as the target in our SGD study. The histogram showing the distribution of ∆d C-O max in the data set of 199 structures (Fig. , in grey) highlights that the mean bond elongation is 0.103 Å. As only a few structures provide bond elongations larger than 0.15 Å, it is clear that the strong activation of CO 2 is an exceptional situation among the different SAA adsorption sites.