Fig. 8. The first two principal components of descriptors of local atomic environments within SrTiO₃(110) 4×1 training data. The projections of the training data and “Opt” test set are depicted as the hexagonally binned background and red dots, respectively. The principal component analysis (PCA) was performed utilizing the scikit-learn library.⁵⁴ To correct for symmetry and recurring environments, the PCA was limited to local environments on one side of each slab, excluding the environments of atoms within fixed bulk-like layers.