In case the overlap of basin I and basin II structures seen in the PCA visualization is due to the dimensional reduction, we also tested density-based clustering in the original, high dimensional descriptor space. The HDBSCAN* algorithm was applied to the same dataset (the GAZCES co-crystal set of local energy minima in P 2 1 /c). However, trying different minimum cluster sizes and, for ACSFs, different measures of the pairwise distance between structures (see ESI), no clustering could be obtained that aligns with the grouping of structures from the threshold simulation results. Full details are given in the ESI. To understand these results, we examined the distributions of distances between structures within each basin and between basins. The distribution of distances between structures was found to be similar within and between energy basins (Figs. 12b, S16, S17, S18), indicating that geometrical similarity based on these atom-centered geometrical descriptors is not necessarily a good indicator of structures that are 'closer', in terms of energetic accessibility, on the energy landscape.