DFT results against experimental data for electronic properties of C60 and C70 fullerene derivatives.

Some electronic properties of different C60 and C70 derivatives were evaluated using 20 density functionals (the B3LYP, BHANDH, PBE0, HSE06, CAM-B3LYP, ωB97X-D, BMK, PBEPBE, M06-L, M06, M06-2X, M06-HF, PW91PW91, BLYP, B97D, HCT407, τ-HCTH, τ-HCTHhyb, TPSS, and LSDA), and some of the results were compared with the available experimental data. Unlike in Hartree-Fock (HF) method, the orbital relaxation is not the origin of the violation of DFT from the Koopmans' theorem. For most of functionals, the HOMO-LUMO gap (Eg) is more sensitive to the functional compared to the optical gap. The functionals with a large %HF exchange significantly overestimate the Eg, and are not suggested for electronic calculations. All non-hybrid functionals underestimate the value of |HOMO| in comparison to the experimental ionization potential (IPe). In the hybrid functionals, the HOMO level becomes more stable by increasing %HF exchange and even in some functionals with a large %HF, |HOMO| overestimates the IPe.