Square root of the merit function adopting the FSM (first panel) and adopting the traditional method with four terms (second panel). Only the PHOENIX-COND models listed in Table 1 are displayed. To guarantee the homogeneity of the comparison the results of the DRIFT models, which were generated adopting a different input physics, are not displayed. Log[A/H] = 0.0; V_ξ = 2 km s⁻¹; TESS photometric system; LSM calculations.