Probability density function (PDF) of the binding energy change, α, per interaction, in the 10k-* models. Binary–single and binary–binary interactions are counted together. For reference, we also plot with dashed vertical lines the theoretical values of α, for which a single m₃-star should theoretically escape, as derived using Eq. (8). The figure is separated by each model’s initial half-mass radius (columns), number and masses of the primordial binaries (rows), and the binary semi-major axes (colours).