Computation and interpretation of Raman scattering intensities

Gough, Kathleen; Lupinetti, Concetta; Dawes, Richard

doi:10.3233/jcm-2004-4406

Cited by 4 publications

(7 citation statements)

References 67 publications

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“…The unique CC bonds in straight-chain alkanes and in simple cycloalkanes may be easily examined with HF and DFT methods [21][22][23]. On stretching the skeleton CC bonds we observe complete reversal of the patterns seen in the CH bonds.…”

Section: Patterns That Emerge In Da/dr CC Of Alkanesmentioning

confidence: 92%

“…Criteria for setting up a successful calculation and options for pushing for the highest accuracy with respect to experiment were recently reviewed [23]; the main points are presented here. The basis set must be large and include diffuse and polarization functions to reproduce experimentally observed behavioral trends.…”

Section: Methodsmentioning

confidence: 99%

“…In the Gaussian implementation, a is calculated by use of the analytical coupledperturbed Hartree-Fock (CPHF) method. More recently, we explored much larger basis sets using a coupled cluster method (CCSD(T)) and applied time-dependent density-functional theory to B3LYP hybrid density functionals [23,24]. We obtained benchmark level calculations that accurately reproduce the Raman intensities for bicyclo-[1.1.1]-pentane to within experimental error.…”

Section: Methodsmentioning

confidence: 99%

“…The intriguing patterns discovered from experiment and supported by ab initio modeling [17][18][19][20][21][22][23][24] raised several new questions, most importantly, whether variation in qa=qr CH might increase with molecular size and complexity. We devised a survey set of thirty-five hydrocarbons comprising the all-trans conformers of n-alkanes up to C 15 , iso-butane, six cycloalkanes and methylcycloalkanes, eight bicycloalkanes, four propellanes, and a tetracyclane [20].…”

Section: Theoretical Modeling Of Raman Scattering Intensities: What Wmentioning

confidence: 99%

“…The larger survey calculations of qa=qr using standard electronic structure calculations include normal and branched alkanes, a diverse selection of cycloalkanes and bicycloalkanes, hedranes and propellanes, and a few alkenes, alkynes, silanes, and extended sheets [22][23][24]. Some of these are shown in Fig.…”

Section: 7mentioning

confidence: 99%

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QTAIM Analysis of Raman Scattering Intensities: Insights into the Relationship Between Molecular Structure and Electronic Charge Flow

Gough

Dawes

Dwyer

et al. 2007

The Quantum Theory of Atoms in Molecules

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The investigation of the interplay between molecular structure and molecular properties is one that still captivates the imagination. The chemist today relies on computational modeling to gain insight into known properties and to help predict the behavior of systems for which experimental data are lacking. This two-way exchange epitomizes the conversation between experimentalists and theoreticians and shows us the way forward in developing our science. New theories breathe new life and meaning into existing experimental techniques and lead to the discovery of new truths and insight. Nature has all the answers and we have but to find them. In this chapter we will outline one such conversation -that between Raman spectroscopy and the quantum theory of atoms in molecules (QTAIM). Absolute Raman scattering intensities are difficult to measure yet they contain much valuable information. As such, they are intrinsically interesting, but they also provide an excellent framework on which to compose another theoretical-experimental conversation. QTAIM brings a unique and critical element to this enterprise; through this analysis, Raman spectroscopy is cast as an extremely sensitive probe of the structural origins of molecular function. We will discover that despite experimental and computational challenges, this dualpronged approach yields great rewards.We have seen in previous chapters the power of real-space analysis and the transferability of some functional group properties but now we will examine nontransferable properties. Nontransferable properties are those molecular properties which cannot be partitioned into functional groups independent of the molecular setting. It must be emphasized that the failure of some molecular properties to partition into neat functional group categories is no failure of QTAIM, but is instead a reflection of nature. The power of QTAIM in these instances is to analyze the detailed electronic distribution using the convenience and familiarity of realspace rather than an unwieldy multidimensional wavefunction. The electron dis- 95The Quantum Theory of Atoms in Molecules. Edited

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Section: Patterns That Emerge In Da/dr CC Of Alkanesmentioning

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Theoretical Modeling Of Raman Scattering Intensities: What Wmentioning

confidence: 99%

Section: 7mentioning

confidence: 99%

See 3 more Smart Citations

QTAIM Analysis of Raman Scattering Intensities: Insights into the Relationship Between Molecular Structure and Electronic Charge Flow

Gough

Dawes

Dwyer

et al. 2007

The Quantum Theory of Atoms in Molecules

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Qualitative and quantitative approach towards the molecular understanding of structural, vibrational and optical features of urea ninhydrin monohydrate

Sasikala¹,

Sajan²,

Chaitanya

et al. 2017

Materials Chemistry and Physics

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In this study, single crystals of urea ninhydrin monohydrate (UNMH) have been grown by slow evaporation method. The grown crystals were characterized by FT-IR, FT-Raman and UV-Vis-NIR spectroscopies. The Kurtz and Perry powder method was employed to confirm the near-zero SHG efficiency of the as-grown centrosymmetric UNMH crystal. The third order nonlinearity of the crystal has been studied by the open aperture Z-scan method. The nonlinear absorption coefficient is calculated and the potentiality of UNMH in optical limiting applications is identified. The molecular geometry and the origin of optical nonlinearity at the molecular level have been investigated by the density functional theory. The normal coordinate analysis was carried out to assign the molecular vibrational modes. Vibrational spectral studies confirms the presence of weak O-H•••O and moderate O-H•••O type hydrogen bonds in the molecule as well as O-H•••O, N-H•••O and blue-shifted C-H•••O type H-bonds in the crystal. The intramolecular charge transfer interactions and the electronic absorption mechanisms have been discussed. The static and the dynamic values of hyperpolarizabilities for UNMH were estimated theoretically by DFT methods.

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Difference in the relative intensities Raman of the perovskite PLT with temperature

Joya¹,

Fonseca²,

Barba-Ortega³

2014

AIP Conference Proceedings

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La-modified PbTiO3 -based ceramics (PLT) are the subject of many studies. The experimental measurement and the theoretical calculation of Raman scattering intensities present a number of challenges. In the treatment of experimental data, anharmonic force fields permit the calculation of combination and overtone intensities as well as the resolution of anharmonic resonances. Vibrational intensities provide information about the molecular charge distribution and its change during a vibration. On most cases Raman scattering is sensitive to the degree of crystallinity in a sample. Typically a crystalline material yields a spectrum with very sharp, intense Raman peaks, whilst an amorphous material will show broader less intense Raman peaks. Intensity reproducibility is not a trivial matter. Furthermore, properties of the sample such as optical transparency and homogeneity can affect observed intensity, even when the overall sample composition is fixed. A corrected spectrum showing relative peak areas (and therefore relative cross-sections) may be sufficient for sample identification. In this paper we make a comparison of the Raman intensities relative to the PLT compound for different temperatures.

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Computation and interpretation of Raman scattering intensities

Cited by 4 publications

References 67 publications

QTAIM Analysis of Raman Scattering Intensities: Insights into the Relationship Between Molecular Structure and Electronic Charge Flow

QTAIM Analysis of Raman Scattering Intensities: Insights into the Relationship Between Molecular Structure and Electronic Charge Flow

Qualitative and quantitative approach towards the molecular understanding of structural, vibrational and optical features of urea ninhydrin monohydrate

Difference in the relative intensities Raman of the perovskite PLT with temperature

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