The Rydberg states of trans-1,3-5-hexatriene from ab initio and configuration interaction calculations

Self-consistent ab initio and configuration interaction (CI) calculations are presented for the Rydberg states of the trans-1,3,5-hexatriene molecule. Seven Rydberg series were identified, four optically allowed (ns, nd _{s ²}, nd ₂₉) and three optically forbidden (np _z, np _y, np _z). These present results plus previous calculations on the valence states are used to assign the transitions observed in the ultraviolet (UV), electron-impact (EI) and two-photon spectra of this molecule.