On the basis of these findings, we further choose 10 functionals with better popularity in material science, including PBE, SCAN, r 2 SCAN-3c, B3LYP, PBE0, M06-2X, MN15, ωB97XD, ωB97X-V and HSE06, and extend above-mentioned DFT calculations to all the molecules in the dataset. Based on our benchmark results shown in Table and Figure , we found that while the qualitative predictions of J and ΔEspin are generally good, quantitative predictions are not yet attainable within the DFT framework, particularly for the systems with relatively weak magnetic coupling and spin-polarization, such as -2 meV for J and -0.5 eV for ΔEspin, where errors in the relative energies between different states are largest. Regarding the mapping approaches, we found that Noodleman's and Yamaguchi's methods yield similar J values, which are generally about twice those predicted by Ruiz's method. (Tables S1-2 and Table ) For example, the predicted J values for TRI dimer are -10.08 meV, -10.53 meV, and -6.76 meV using Noodleman's, Yamaguchi's, and Ruiz's methods, respectively, in comparison to the reference value of 7.88 meV. This overestimation of J, as predicted by Noodleman's and Yamaguchi's approaches, has been consistently reported in the literature, particularly for organic diradical systems. Consequently, scaling factors of 0.3-0.5 have been employed to align with experimental J values. As demonstrated in Figure , Tables approach. Thus, at least from a numerical perspective, Ruiz's method appears more suitable for extracting J from BS-DFT for these metal-free systems. Hereafter, the detailed analysis of the functionals' performance will be grounded in the results obtained using Ruiz's approach.