Previous research attributed the vanishing HOMO-LUMO gap to two main reasons: the intrinsic density delocalization error for DFAs 2 and the electric field caused by the surface dipole of proteins. CPCM could eliminate the second factor by inducing solvent polarization charges to screen this electric field. Therefore, the HOMO-LUMO gap can be gradually recovered when e increases. In contrast, the non-charge-separated peptides' surface charges have much smaller magnitudes, as indicated by the relatively low dipole moments (Figure and Supplementary Material Table ). Hence, the non-charge-separated peptides do not suffer from the vanishing gap problem and benefit little from CPCM's SCF acceleration effect.