A theoretical study of the electronic spectrum of styrene

The electronic spectrum of styrene has been studied by using multiconfigurational second-order perturbation theory (CASPT2). The study includes geometry optimization of the ground state, the lowest triplet state, and the lowest singlet excited state. The covalent 21A′ state placed vertically at 4.34 eV is assigned to the first band. The 11A′→31A′ transition located at 4.97 eV is responsible for the second band. The most intense feature involves the 51A′ state, which is calculated to lie 6.19 eV above the ground state. The lowest singlet–singlet Rydberg transition (3s) is predicted to occur at 5.85 eV.