Optimized input parameters (left) and results at the solar age (right). The left panels show α_MLT, f_overshoot, Y_proto, Z_proto, and stellar mass (M₁ and M₂) for nine models from top to bottom. The right panels show the χ² value (see Eq. (8)), rms(δc_s), (Z/X)_surf, Y_surf and R_CZ from top to bottom. The five models shown in each panel are: non-accreting models with GS98 composition (Runs 2 and 4); non-accreting models with AGSS09 composition (Runs 1 and 3); accreting models with time-dependent Z_acc (Runs 7 and 8); models with He-poor accretion (Runs 5 and 6); and K2 model (Run 9) with A₂ = 0.12, from left to right (see Table 1 for details). Squares and crosses represent the cases with and without overshooting, respectively. Diamonds and asterisks represent the cases with He-poor accretion for t_acc = 12 and 20 Myr, respectively. The shaded regions in the right panels indicate χ² < 1 or the 1σ uncertainties (see Table 3).