Comparing the Standard and Hierarch models, we find that predicted pressures, RDFs, and vibrational power spectra are of similar accuracy (see Supplementary Information Table and Figure ). Particularly notable exceptions to this are shown in Figure , where for low density, high temperature carbyne-like state points, the Standard model yields poor recovery of the corresponding RDFs. This result is unsurprising, since the system structures are dissimilar from anything in the C/N training set (see Figure ). Additionally, we find that diffusion coefficients for C at 6000 K and 2.5 g cm 3 and 7000 K and 2 g cm 3 are significantly over predicted relative to DFT (see Figure ). As shown in Table , we find the Standard model performs notably worse when predicting diamond and graphite lattice parameters, which is surprising since the C/N training data contains both graphite-like configurations and high density liquid. In particular, our 2017 ChIMES-Carbon model 7 was trained to only a single liquid carbon state point, yet produced a significantly improved diamond lattice parameter (i.e., a = 3.565 Å).