Complementary insights can be obtained if we instead analyze the processes not by the total number of atoms that are significantly displaced, but by the species type. Figure shows the corresponding 10 such classes with most processes. This reveals that about 40% of all identified processes involve the exclusive motion of Pd atoms. Most of these involve the displacement of Pd 1 or Pd 2 units as one would expect in one-atom surface hopping or two-atom exchange diffusion type surface diffusion processes. However, there are also 148 unique collective processes involving Pd 3+ units. This reflects a high complexity of even just metal surface and edge diffusion well beyond the classical mechanisms -a realization that had also been emphasized in previous works. About 10% of all identified processes concern the mere diffusion of single O atoms (O 1 in Fig. ). Overall, the movement of O is much faster than Pd (see Fig.