Properties of primordial binaries adopted in our simulations, shown for one representative cluster realisation with initial mass m_SC ≈ 9.8 × 10⁴ M_⊙ and initial half-mass radius r_h ≈ 4 pc. Left panel: mass distribution of primary stars (m₁) in binaries and single stars (m_sing). Both populations are sampled from a Kroupa IMF. Central panel: distribution of binary orbital eccentricities (ecc) as a function of period (log(P) in days). The red curve marks the exclusion boundary (Eq. (3) in Moe & Di Stefano 2017), to avoid Roche lobe filling binaries. Right panel: mass-dependent binary fraction ( f_bin) in our realisation (blue points) compared to observational constraints from Moe & Di Stefano (2017).