The gradient norms were also a part of the optimization scheme (Equation ). Figure shows the gradient norms given by the xtb program for the two parameterizations. The structures are equilibrium structures at the ωB97X-D/6-31++G(d,p) level of theory, so the ideal gradient norms should be below the default gradient convergence thresholds of 10 -3 Eh/α. None of the methods manages to be below this threshold, but the AMC-xTB model is close. This does not directly mean the model is closer to the correct structure, as the new parameters might just have flattened the potential energy surface at this point without moving closer to the minimum. However, including the gradients in the target function avoids numerical instability, and yields reasonable optimized structures. To test if the structures are closer to a minimum at the DFT level, the initial DFT structures of all three datasets were optimized using the different parameterizations, and the RMSD was computed between the initial DFT structure and the GFN1-xTB/AMC-xTB optimized structures (see Table ).