Transition1x 12 was downloaded as provided. From the roughly 10M data points of 10,073 reactions, we only kept the last, converged reaction pathways, where each pathway is made up of 10 images of the NEB search, resulting in 100k data points. The dataset was then split into a training and validation fraction made up of structures of the first or last two images (index 1, 2, 9, 10) in the NEB search (40k data points), corresponding to the equilibrated reactants, products, and configurations close to these equilibrated structures. All other image indices were put into the test set (60k data points). This split allows us to explore the correlation of epistemic uncertainty with the absolute error for regions the model has never seen, namely non-equilibrium configurations along diverse reaction paths. Since the image indices are known for all data points, we can evaluate the correlation as a function of the distance to the training image indices, and therefore explore mild (index 3, 8) to strong (index 5, 6) out-of-distribution examples.