Moving to PLY-6N (Fig. ), both dark and bright states again first blue-shift when the aza nitrogen PPP on-site energy is made more negative (i.e., -2eV< ε N <0), and then red-shift for ε N going from -3 eV to -6 eV. Here, the dark 2 A ′′ 2 state lies below the bright one for ε N ≤ -5 eV. Similarly to PLY-3N, both |⟨ D⟩| (panel f) and oscillator strength of the 2 E ′′ ← 2 A ′′ 1 transition (panel g) show a minimum for ε N = -2 eV, increasing for either