Vibrational and electronic second hyperpolarizabilities of all-trans polysilane chains

Perpète, Éric A.; André, Jean‐Marie; Champagne, Benoı̂t

doi:10.1063/1.477067

Cited by 22 publications

(9 citation statements)

References 101 publications

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“…͑12͒ which causes the anharmonic term to predominate. This is consistent with results found earlier by Perpète et al 14,53 As we have just seen, anharmonicity plays a crucial role in the vibrational dc-Kerr effect of PSi due to the nearcancellation of two large zeroth-order terms. This situation does not occur in the -conjugated oligomers.…”

Section: IIsupporting

confidence: 82%

“…This means that for most purposes the latter is negligible compared to the electronic term. In PSi ␥ L v(r) (Ϫ2 ; , ,0) →ϱ has been attributed, 14 for the most part, to H-wagging modes which induce substantial electron density polarization along the chain.…”

Section: IImentioning

confidence: 99%

“…1,2 In contrast with small molecules, the vibrational contribution will, typically be as important as its electronic counterpart 3,4 for large conjugated organic ͑or inorganic͒ molecules and oligomers [5][6][7][8][9][10][11][12][13][14] of interest as NLO materials. In fact, the static vibrational and electronic hyperpolarizabilities of such systems are often approximately equal, 15,16 although there are also important exceptions.…”

Section: Introductionmentioning

confidence: 99%

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Anharmonicity contributions to the vibrational second hyperpolarizability of conjugated oligomers

Champagne

Luis

Duran

et al. 2000

The Journal of Chemical Physics

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Restricted Hartree-Fock 6-31G calculations of electrical and mechanical anharmonicity contributions to the longitudinal vibrational second hyperpolarizability have been carried out for eight homologous series of conjugated oligomers-polyacetylene, polyyne, polydiacetylene, polybutatriene, polycumulene, polysilane, polymethineimine, and polypyrrole. To draw conclusions about the limiting infinite polymer behavior, chains containing up to 12 heavy atoms along the conjugated backbone were considered. In general, the vibrational hyperpolarizabilities are substantial in comparison with their static electronic counterparts for the dc-Kerr and degenerate four-wave mixing processes ͑as well as for static fields͒ but not for electric field-induced second harmonic generation or third harmonic generation. Anharmonicity terms due to nuclear relaxation are important for the dc-Kerr effect ͑and for the static hyperpolarizability͒ in the -conjugated polymer, polysilane, as well as the nonplanar systems polymethineimine and polypyrrole. Restricting polypyrrole to be planar, as it is in the crystal phase, causes these anharmonic terms to become negligible. When the same restriction is applied to polymethineimine the effect is reduced but remains quantitatively significant due to the first-order contribution. We conclude that anharmonicity associated with nuclear relaxation can be ignored, for semiquantitative purposes, in planar -conjugated polymers. The role of zero-point vibrational averaging remains to be evaluated.

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Section: IIsupporting

confidence: 82%

Section: IImentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Anharmonicity contributions to the vibrational second hyperpolarizability of conjugated oligomers

Champagne

Luis

Duran

et al. 2000

The Journal of Chemical Physics

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“…Our new approach is based on the determination of a small number of vibrational coordinates that exactly reproduce the BHK results for the complete vibrational space. There are quite a few calculations in the literature which show that, for longitudinally extended conjugated molecules or oligomers, 1,7,20 the double harmonic vibrational polarizabilities and hyperpolarizabilities are often dominated ͑at least, at the Hartree-Fock level͒ by contributions from a limited number of normal modes. However, no prescription has been given for determining the precise form of these modes or for predicting when other modes may become important.…”

Section: Introductionmentioning

confidence: 99%

Determination of vibrational polarizabilities and hyperpolarizabilities using field-induced coordinates

Luis

Duran

Champagne

et al. 2000

The Journal of Chemical Physics

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167

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An analytical set of field-induced coordinates ͑FICs͒ is defined. It is shown that, instead of 3N Ϫ6 normal coordinates, a relatively small number of FICs is sufficient to describe the vibrational polarizability and hyperpolarizabilities due to nuclear relaxation. The fact that the number of FICs does not depend upon the size of the molecule leads to computational advantages. A method is provided for separating anharmonic contributions from harmonic contributions as well as effective mechanical from electrical anharmonicity. Hartree-Fock calculations on a dozen representative conjugated molecules illustrate the procedures and indicate that anharmonicity can be very important. Other potential applications including the determination of zero-point vibrational averaging corrections are noted.

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“…3,4 Nonlinear optical materials have been extensively studied for many years. [5][6][7][8][9] To design and fabricate NLO materials much effort is being devoted to understand the origin of non-linearity in large systems and to relate NLO responses to electronic structure and molecular geometry. Significant interest still exists in the design and development of materials exhibiting large second-order NLO response because of the potential application in telecommunications, optical computing, optical signal processing, laser technology, data storage and image processing.…”

Section: Introductionmentioning

confidence: 99%

Studies on crystal growth, vibrational, dielectric, electronic, mechanical and thermal properties of new organic nonlinear optical crystal: 3-nitrocinnamic acid

Alen

Sajan²,

Sabu³

et al. 2013

CrystEngComm

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3-Nitrocinnamic acid (3NCA) was synthesized and its crystals were grown in aqueous solution by slow evaporation solution growth technique. The grown crystal was confirmed by powder XRD studies. The geometry, intermolecular hydrogen bonding, and harmonic vibrational wavenumbers of 3NCA were investigated with the help of B3LYP density functional theory (DFT) methods. The calculated molecular geometry has been compared with the experimental data obtained from XRD data. The assignments of the vibrational spectra have been carried out with the aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFF). Vibrational spectral investigation confirms the formation of cyclic dimers in the crystal, with the carboxyl groups of each acid molecule bonded to those of adjacent molecules. The red shift of the O-H stretching wavenumber is due to the formation of strong O-H⋯O hydrogen bonds by hyperconjugation between the carbonyl oxygen lone electron pairs and the O-H σ* antibonding orbitals. Thermal stability of the grown crystal was examined by recording TGA/DTA. Mechanical strength of the grown material was tested by hardness studies. Second harmonic frequency generation was examined by Kurtz and Perry powder test and it reveals that the relative conversion efficiency is 0.8 times greater than that of urea. The theoretical first order hyperpolarizability value was calculated for the optimized structure.

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Vibrational and electronic second hyperpolarizabilities of all-trans polysilane chains

Cited by 22 publications

References 101 publications

Anharmonicity contributions to the vibrational second hyperpolarizability of conjugated oligomers

Anharmonicity contributions to the vibrational second hyperpolarizability of conjugated oligomers

Determination of vibrational polarizabilities and hyperpolarizabilities using field-induced coordinates

Studies on crystal growth, vibrational, dielectric, electronic, mechanical and thermal properties of new organic nonlinear optical crystal: 3-nitrocinnamic acid

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