Particularly, SCAN works surprisingly well for the triangulene monomer and predicts the J of 468.41 meV and ΔEspin of -1.4 eV, yet less accurately for the dimer with relative errors of 119% and -24%. This suggests that SCAN may be suitable to describe systems with strong magnetic coupling. It is also observed that double hybrid functionals generally produce unreliable results for both the monomer and dimer, potentially leading to incorrect ground states (Table and Figure ). For example, B2GP-PLYP and ωB97X-2 erroneously predict an OSS ground state for the monomer and a highspin state for the dimer. Although B2PLYP could correctly indicate the ground state, the J values are overestimated by 23% and 216% for the monomer and dimer, respectively.