title: S1 and S2 excited states of gas-phase Schiff-base retinal chromophores: a time-dependent density functional theoretical investigation.
abstract: In concert with the recent photoabsorption experiments of gas-phase Schiff-base retinal chromophores (Nielsen et al. Phys. Rev. Lett. 2006, 96, 018304), quantum chemical calculations using time-dependent density functional theory coupled with different functionals and under the Tamm-Dancoff approximation were made on the first two excited states (S1 and S2) of two retinal chromophores: 11-cis and all-trans protonated Schiff bases. The calculated vertical excitation energies (Tv) and oscillator strengths (f) are consistent with the experimental absorption bands. The experimentally observed phenomenon that the transition dipole moment (mu) of S2 is much smaller that of S1 was interpreted by 3D representation of transition densities. The different optical behaviors (linear and nonlinear optical responds) of the excited states were investigated by considering different strengths of external electric fields.
authors: National Laboratory for Condensed State Matter Physics, Institute of Physics, Chinese Academy of Sciences, P. O. Box 603-146, Beijing 100080, China. mtsun@aphy.iphy.ac.cn
authors: Mengtao
authors: M
authors: Sun
authors: Yong
authors: Y
authors: Ding
authors: Ganglong
authors: G
authors: Cui
authors: Yajun
authors: Y
authors: Liu
mesh_terms: D000818:Animals; D002627:Chemistry, Physical / Q000379:methods; D004563:Electrochemistry; D007093:Imidazoles / Q000737:chemistry*; D008027:Light; D008956:Models, Chemical; D008962:Models, Theoretical; D008968:Molecular Conformation; D009991:Oscillometry; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D011687:Purines / Q000737:chemistry*; D012160:Retina / Q000378:metabolism*; D012545:Schiff Bases / Q000737:chemistry*; D012984:Software; D013997:Time Factors; D014785:Vision, Ocular
chemical_list: C438613:8-ethyl-4-methyl-2-phenyl-4,5,7,8-tetrahydro-1H-imidazo(2,1-i)purin-5-one; D007093:Imidazoles; D045332:Photosystem II Protein Complex; D011687:Purines; D012545:Schiff Bases; C093489:photosystem II, psbT subunit