A CASSCF study of the S0 and S1 states of phenol

Different basis sets and active spaces have been employed to determine the geometries and vibrational frequencies of phenol in its electronic ground and first excited state at the CASSCF level of theory. Good agreement with experimentally determined rotational constants was achieved using Dunningʹs correlation consistent cc-pVDZ basis set. The electronic origin of the S1 ← S0 excitation has been calculated with an accuracy of 0.1 eV considering zero-point energy corrections for both the S0 and S1 states. Additionally, S1 state frequencies were calculated at the CIS/cc-pVDZ level of theory.