From the transition probabilities of Figure , it is possible to estimate the average lifetime of the various AEs and the transition rates between them. In particular, the off-diagonal entries (p i→ j ) divided by dt give the transition rates between two AEs i → j, k i→ j , from which one can estimate the characteristic timescales for the various transitions as: τ i→ j = k -1 i→ j . The number of times a given transition event i → j is registered in the system along the last 1000 ns is reported in Supplementary Figure as explicitly counted along the MD simulation, or it can be also estimated as: n i→ j = [i] • 1000/τ i→ j , where [i] is the average number of atoms in the i th AE (Supplementary Figure ). For example, in the Ih 309 NP at 300 K an atom in the Faces AE (dark-green) has a transition probability to the Edges AE (light-green) of p Faces→Edges ∼ 0.12 (∼ 12 × 10 -2 ), indicating a transition rate of k Faces→Edges ∼ 0.12 ns -1 and characteristic transition timescale τ Faces→Edges ∼ 8.3 ns (Supplementary Figures and: transition event observed ∼ 6700 times along the last 1 µs of MD simulation). Furthermore, since this is the fastest transition involving the Faces AE, this sets the bottom limit for the lifetime of an atom in the (111) faces of this NP at 300 K (minimum residence time) as τ Faces ∼ 8.3 ns.