Notably, the 3.2k model already displays a very large AE error of more than 10 eV at 300 K. The MD error is thus orders of magnitude larger than the test set error, even though these configurations should arguably fall within the scope of the training set. This mainly stems from the fact that the trajectories for certain molecules lead to completely unphysical configurations, for which the potential then displays extremely large errors. Such unphysical configurations also commonly lead to convergence issues in the reference DFT calculations. To quantify this, the percentage of converged DFT calculations for configurations obtained with a given potential and simulation temperature is shown in Fig. . We find that all DFT calculations converge for the 320k and 3.2Mio potentials, while the sparse models generate increasingly unphysical configurations with rising temperature. This is particularly evident for the 3.2k model at 1200 K, where only about half of the DFT calculations converge.