Calculations of the absorption spectrum of chromone

We have performed a theoretical investigation of the optical properties of the molecule chromone, using multireference perturbation theory (CASPT2) an d time-dependent density functional theory (DFT) methods. The structure of the molecule was optimized at the DFT level and at the level of complete ac tive space self-consistent field (CASSCF). In addition to vertical excitati on energies, we have computed the lowest adiabatic (1)A' transition energy, as well as transition probabilities for all singlet transitions to low-lyi ng states. Using this data, we can assign the four observed ultraviolet abs orption peaks of chromone. Finally, we address the question of the aromatic ity of the heterocyclic ring in chromone, an issue which has recently recei ved some attention.