title: On the vertical excitation energy of cyclopentadiene.
abstract: The vertical excitation energy for the lowest valence pi-->pi(*) transition of cyclopentadiene is investigated. Using a combination of high-level theoretical methods and spectroscopic simulations, the vertical separation at the ground state geometry is estimated to be 5.43+/-0.05 eV. This value is intermediate between those calculated with coupled-cluster and multireference perturbation theory methods and is about 0.13 eV higher than the observed maximum in the absorption profile.
authors.affiliation: Department of Chemistry, Institute for Theoretical Chemistry, The University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: Yannick J
authors.initials: YJ
authors.lastname: Bomble
authors.forename: Kurt W
authors.initials: KW
authors.lastname: Sattelmeyer
authors.forename: John F
authors.initials: JF
authors.lastname: Stanton
authors.forename: Jürgen
authors.initials: J
authors.lastname: Gauss