Figure 2.

LIIC pathways connecting the ground-state optimized geometry, S₀ (min), to the first excited optimized geometry, S₁ (PICT), of Nile Red. Calculations were performed in an implicit solvent model for (a) 1-pentanol and (b) n-hexane. Insets in panel a depict the natural transition orbitals associated with absorption and fluorescence between the S₀ and S₁ states. In panel b, the transition dipole moments corresponding to the S₁←S₀ transition at S₀ (min) and S₁ (PICT) are overlaid on the respective minimum energy structures. The shaded purple area in both panels represents the magnitude of the S₁ ← S₀ oscillator strength along the LIIC pathway. The large purple dot in each panel corresponds to the solvent relaxed S₁ minimum energy calculated using equilibrium IEFPCM. All calculations were performed with DFT/ωB97XD/def2-TZVPP and LR-TDDFT/TDA/ωB97XD/def2-TZVPP using a nonequilibrium IEFPCM solvent model.