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The long-range correction (LC) for treating electron exchange in density functional theory, combined with the Becke–Lee–Yang–Parr (BLYP) exchange-correlation functional, was used to determine (hyper)polarizabilities of polydiacetylene/polybutatriene oligomers. In comparison with coupled-cluster calculations including single and double excitations as well as a perturbative treatment of triple excitations, our values indicate that the tendency of conventional functionals to result in a catastrophic overshoot for these properties is alleviated but not eliminated. No clear-cut preference for LC-BLYP over Hartree–Fock values is obtained. This analysis is consistent with the calculations of Sekino et al. [J. Chem. Phys. 126, 014107 (2007)] on polyacetylene and molecular hydrogen oligomers. Thus, the performance of LC-BLYP with regard to (hyper)polarizabilities of quasilinear conjugated systems is now well characterized. [ABSTRACT FROM AUTHOR]

Hyper-Raman spectra of pure carbon tetrachloride in the liquid phase are recorded for different combinations of the polarizations of the incident and scattered lights and are compared to ab initio time-dependent Hartree-Fock simulations. Both the calculated intensities of the Raman and hyper-Raman spectra give indeed a quite satisfactory agreement with polarized experimental spectra. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A convenient and efficient three-step route is developed for both symmetrically and asymmetrically functionalized 4H-cyclopenta[2,1-b:3,4-b' ]dithiophenes. The replacement of the dialkyl reagent by ethyl levulinate has helped in preparing an ester-functionalized 4H-cyclopenta[2,1-b:3,4-b' ]dithiophene, which has represented a precursor for cyclopentadithiophene compounds.

The second-order nonlinear optical properties of green fluorescent proteins (GFPs) like the photoswitchable Dronpa and enhanced GFP (EGFP) are studied. The second-order nonlinear optical properties of GFP-like proteins are important for the combined nonlinear microscopy based on existing fusion proteins involving GFPs.

The time-dependent density functional theory is employed to study the geometries and resonance Raman scattering of different excited states of rhodamine 6G (R6G) in vacuum and ethanol. The different states are shown to exhibit similar vibronic but different solvent effects and structure.

A study was conducted to determine the keto-amine/enol-imine tautomerization equilibrium in a series of substituted salicylideneanilines. The finding from the study could be applied to design compounds with a contrast of second-order nonlinear optical properties.

Density functional theory and a hybrid exchange-correlation functional are used for investigating the relationship between the second hyperpolarizability ([gamma]) and the diradical character for diphenalenyl-based compounds containing different heterocyclic five-membered central rings or substituted by donor/acceptor groups. New relationships between the chemical structures and the second hyperpolarizabiliies are rationalized, particularly those involving the control of the diradical character in diphenalenyl compounds.

The synthesis and characterization of the linear and nonlinear optical properties of benzothiazolo[2,3-b]oxazolidine acidochromes by using hyper-Rayleigh scattering and quantum chemical calculations are presented. The results have shown that the benzothiazolium acceptor is more effective than the indoleninium one and the elongation of ethylenic bridging unit to a 2,5-diethenylthiophene has increased the nonlinear optical (NLO) response of the protonated open form (POF) by a factor of 6.

The time-dependent density functional theory is used to experimentally estimate the visible as well as ultraviolet (UV) spectral properties of different families of merocyanine dyes and to hence compare it with the theoretical estimations already available. The analysis reveals that the methodology used very wisely uses the least-square fits to correct and minimize the major systematic errors, which are originated because of the description of the solvents, as well as from the vibronic effects.

The synthesis of a series of N,N'-substituted naphthidines using the nickel-catalyzed aryl amination methodology and the determination of their electronic and magnetic properties by several electrochemical techniques are described. The results reveal that naphthidines exhibit good donor properties, showing a single two-electron oxidation wave to form the di(radical cation) species naphthidines(super 2.2+) that display remarkable stability at room temperature in solution and in the solid state.