title: Ground and excited states of retinal schiff base chromophores by multiconfigurational perturbation theory.
abstract: We have studied the wavelength dependence of retinal Schiff base absorbencies on the protonation state of the chromophore at the multiconfigurational level of theory using second order perturbation theory (CASPT2) within an atomic natural orbital basis set on MP2 optimized geometries. Quantitative agreement between calculated and experimental absorption maxima was obtained for protonated and deprotonated Schiff bases of all-trans- and 11-cis-retinal and intermediate states covering a wavelength range from 610 to 353 nm. These data will be useful as reference points for the calibration of more approximate schemes.
authors.affiliation: Department of Chemistry, University of Duisburg-Essen, Campus Duisburg, D-47048 Duisburg, Germany.
authors.forename: Sivakumar
authors.initials: S
authors.lastname: Sekharan
authors.forename: Oliver
authors.initials: O
authors.lastname: Weingart
authors.forename: Volker
authors.initials: V
authors.lastname: Buss
mesh_terms: D003198:Computer Simulation; D007536:Isomerism; D008027:Light; D008956:Models, Chemical; D008958:Models, Molecular; D017785:Photons; D011789:Quantum Theory; D012172:Retinaldehyde / Q000737:chemistry* / Q000528:radiation effects*; D012545:Schiff Bases / Q000737:chemistry* / Q000528:radiation effects*
chemical_list: D012545:Schiff Bases; D012172:Retinaldehyde