program. We used this occasion to compare the numerical differences between the Gaussian 16 and ORCA 5.0 programs. Even though the numerical values of J and ΔEspin correspond to small energies, the calculations at B3LYP/def2-TZVP level are consistent for all cases studied with difference of the target quantities within 2% (Table ). As shown in Figure and Table , the hybrid functionals generally provide a more accurate prediction of the J and ΔEspin with MAE of 110.1 meV and 0.25 eV for the monomer and 1.7 meV and 0.74 eV for the dimer compared to those from GGA and meta-GGA functionals of 218.6 meV and 0.50 eV for the monomer and 3.9 meV and 1.7 eV for the dimer. Among them, for the dimer, PBE0, MN15 and ωB97M-V give the best prediction of -9.73 meV, -8.90 meV and -10.07 meV for the J and -1.99 eV, -2.40 eV and -2.80 eV for the ΔEspin with reference to -7.88 meV for the J and -2.68 eV for the ΔEspin. As for the monomer, ωB97XD and ωB97M-V predict the J values of 449.52 meV and 455.30