Time evolution of the bound fraction F_b of isolated models (N = 10⁴) as defined by two methods: defined by the fraction of stars with a negative total energy (solid lines), and defined by recalculating the total energy of stars in an iterative process (see text for details; dashed lines). The vertical dotted line corresponds to t = 20 Myr when we scale the isolated models with the same scale factor as for a non-isolated model with M_⋆ = 6000 M_⊙, which also has N ≈ 10⁴.