title: Analytic density functional theory calculations of pure vibrational hyperpolarizabilities: the first dipole hyperpolarizability of retinal and related molecules.
abstract: We present a general approach for the analytic calculation of pure vibrational contributions to the molecular (hyper)polarizabilities at the density functional level of theory. The analytic approach allows us to study large molecules, and we apply the new code to the study of the first dipole hyperpolarizabilities of retinal and related molecules. We investigate the importance of electron correlation as described by the B3LYP exchange-correlation functional on the pure vibrational and electronic hyperpolarizabilities and compare the computed hyperpolarizabilities with available experimental data. The effects of electron correlation on the pure vibrational corrections vary signficantly even between these structurally very similar molecules, making it difficult to estimate these effects without explicit calculations at the density functional theory level. As expected, the frequency-dependent first hyperpolarizability, which determines the experimentally observed second-harmonic generation, is dominated by the electronic term, whereas for the static hyperpolarizability, the vibrational contribution is equally important. As a consequence, frequency extrapolation of the measured optical hyperpolarizabilities can only provide an estimate for the electronic contribution to the static hyperpolarizability, not its total value. The relative values of the hyperpolarizabilities for different molecules, obtained from the calculations, are in reasonable agreement with experimental data.
authors.affiliation: Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø-The Arctic University of Norway , N-9037 Tromsø, Norway.
authors.forename: Bin
authors.initials: B
authors.lastname: Gao
authors.forename: Magnus
authors.initials: M
authors.lastname: Ringholm
authors.forename: Radovan
authors.initials: R
authors.lastname: Bast
authors.forename: Kenneth
authors.initials: K
authors.lastname: Ruud
authors.forename: Andreas J
authors.initials: AJ
authors.lastname: Thorvaldsen
authors.forename: Michał
authors.initials: M
authors.lastname: Jaszuński
mesh_terms: D004583:Electrons; D011789:Quantum Theory; D012172:Retinaldehyde / Q000737:chemistry*; D014732:Vibration
chemical_list: D012172:Retinaldehyde