A Appendix

A.1 Graph-building strategies The graphs were built using the IsayevNN class from the pymatgen [48] package. It implements the commonly used Voronoi tessalation to define neighbors. Two atoms are considered bonded if they share a face in the Voronoi tessalation of the supercell and their distance is less than the sum of the atomic Cordero radii (a measure of the atomic radius) plus a cutoff =0.5Å. This value of the cutoff was increase compared to [32] to reduce the number of disconnected graphs. We provide statistics for the graphs obtained by the method described in Section 5. A hard cutoff on atomic distances of 6Å is also imposed on atomic distances.