Ab initio analysis of C-H and C-C stretching intensities in Raman spectra of hydrocarbons

2000 ◽  
Vol 78 (7) ◽  
pp. 1035-1043 ◽  
Author(s):  
Kathleen M Gough ◽  
Jason R Dwyer ◽  
Richard Dawes
Keyword(s):  
Raman Scattering ◽  
Ab Initio ◽  
Chain Length ◽  
Raman Spectra ◽  
Atoms In Molecules ◽  
Molecular Polarizability ◽  
Saturated Hydrocarbons ◽  
Work Location ◽  
Location Type ◽  
Significant Factors

Molecular polarizability and changes in the polarizability associated with the stretch of C–C and C–H bonds have been calculated for thirty-four saturated hydrocarbons, including the series of n-alkanes to C15, as well as several cyclo- and bicycloalkanes, propellanes, prismanes, and hedranes. The ab initio results (HF/D95(d,p)) are compared to experimental Raman trace scattering intensities where such information is available. Possible factors governing trends in the magnitude of the derivatives are considered. For the C–C stretches, chain length and position along the chain are the most important factors for the n-alkanes, whereas strain appears to be significant for the ring and caged structures. For the C–H stretches, the most significant factors are the same as those found in our earlier work: location, type, and orientation relative to the carbon skeleton.Key words: hydrocarbons, Raman scattering intensities, molecular polarizability, polarizability derivatives, theory of atoms in molecules.

Analysis of molecular polarizabilities and polarizability derivatives in H2, N2, F2, CO, and HF, with the theory of atoms in molecules

1996 ◽  
Vol 74 (6) ◽  
pp. 1139-1144 ◽  
Author(s):  
Kathleen M. Gough ◽  
Margaret M. Yacowar ◽  
Richard H. Cleve ◽  
Jason R. Dwyer
Keyword(s):  
Charge Transfer ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Atoms In Molecules ◽  
Molecular Polarizability ◽  
Molecular Orbital Calculations ◽  
Induced Dipole ◽  
Order Of Magnitude ◽  
Atomic Dipole ◽  
Molecular Polarizabilities

Ab initio molecular orbital calculations have been performed on the title molecules at the SCF-HF and MP2 levels to obtain molecular polarizabilities and the derivatives associated with bond stretch. The wave functions from these calculations have been analyzed with the theory of atoms in molecules (AIM). Both the polarizability and its derivative are successfully reconstructed from AIM terms representing the transfer of charge between atoms (CT = charge transfer) and the rearrangement of charge within an atomic basin (AD = atomic dipole). The results for the diatomics are compared to each other and to the alkanes studied previously. Equilibrium polarizabilities are qualitatively explained with reference to atomic electronegativity and type of bonding. While derivatives of the mean molecular polarizability differ by a factor of two at most, individual contributions vary by an order of magnitude. The derivatives along the bond axis for H2 are ΔCT = 2.06 and ΔAD = −0.62 × 10−30 C m/V, while for N2 they are ΔCT = 13.77 and ΔAD = −10.00 × 10−30 C m/V. The common feature observed is that as the induced dipole due to charge transfer increases, the induced dipole due to changes in the atomic dipole also increases and opposes it. Key words: diatomic molecules, molecular polarizability, molecular polarizability derivative, theory of atoms in molecules, ab initio molecular orbital calculations.

Infrared and Raman Spectra, conformations,ab initio calculations and spectral assignments of 1,3-disilabutane (SiH3CH2SiH2CH3)

2007 ◽  
Vol 38 (9) ◽  
pp. 1159-1173 ◽  
Author(s):  
Gamil A. Guirgis ◽  
Paul M. Mazzone ◽  
Daniel N. Pasko ◽  
Peter Klaeboe ◽  
Anne Horn ◽  
...  
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Raman Spectra ◽  
Infrared And Raman Spectra

scholarly journals Phonons in Short-Period GaN/AlN Superlattices: Group-Theoretical Analysis, Ab initio Calculations, and Raman Spectra

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 286
Author(s):  
Valery Davydov ◽  
Evgenii Roginskii ◽  
Yuri Kitaev ◽  
Alexander Smirnov ◽  
Ilya Eliseyev ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Raman Spectra ◽  
Density Functional ◽  
Structural Characteristics ◽  
Vibrational Modes ◽  
Phonon Modes ◽  
Short Period ◽  
Group Theoretical Analysis

We report the results of experimental and theoretical studies of phonon modes in GaN/AlN superlattices (SLs) with a period of several atomic layers, grown by submonolayer digital plasma-assisted molecular-beam epitaxy, which have a great potential for use in quantum and stress engineering. Using detailed group-theoretical analysis, the genesis of the SL vibrational modes from the modes of bulk AlN and GaN crystals is established. Ab initio calculations in the framework of the density functional theory, aimed at studying the phonon states, are performed for SLs with both equal and unequal layer thicknesses. The frequencies of the vibrational modes are calculated, and atomic displacement patterns are obtained. Raman spectra are calculated and compared with the experimental ones. The results of the ab initio calculations are in good agreement with the experimental Raman spectra and the results of the group-theoretical analysis. As a result of comprehensive studies, the correlations between the parameters of acoustic and optical phonons and the structure of SLs are obtained. This opens up new possibilities for the analysis of the structural characteristics of short-period GaN/AlN SLs using Raman spectroscopy. The results obtained can be used to optimize the growth technologies aimed to form structurally perfect short-period GaN/AlN SLs.

scholarly journals Resonance and antiresonance in Raman scattering in GaSe and InSe crystals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Osiekowicz ◽  
D. Staszczuk ◽  
K. Olkowska-Pucko ◽  
Ł. Kipczak ◽  
M. Grzeszczyk ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Temperature Effect ◽  
Band Gap ◽  
Raman Spectra ◽  
Quantum Interference ◽  
Optical Band Gap ◽  
Phonon Coupling ◽  
Phonon Modes ◽  
Electron Phonon Coupling ◽  
Resonant Raman

AbstractThe temperature effect on the Raman scattering efficiency is investigated in $$\varepsilon$$ ε -GaSe and $$\gamma$$ γ -InSe crystals. We found that varying the temperature over a broad range from 5 to 350 K permits to achieve both the resonant conditions and the antiresonance behaviour in Raman scattering of the studied materials. The resonant conditions of Raman scattering are observed at about 270 K under the 1.96 eV excitation for GaSe due to the energy proximity of the optical band gap. In the case of InSe, the resonant Raman spectra are apparent at about 50 and 270 K under correspondingly the 2.41 eV and 2.54 eV excitations as a result of the energy proximity of the so-called B transition. Interestingly, the observed resonances for both materials are followed by an antiresonance behaviour noticeable at higher temperatures than the detected resonances. The significant variations of phonon-modes intensities can be explained in terms of electron-phonon coupling and quantum interference of contributions from different points of the Brillouin zone.

Infrared and Raman spectra, vibrational assignment, and ab initio calculations of fluoromalononitrile

1997 ◽  
Vol 53 (12) ◽  
pp. 2001-2012 ◽  
Author(s):  
M. Dakkouri ◽  
A. Grunvogel-Hurst ◽  
Gamil A. Guirgis ◽  
Zhenhong Yu ◽  
Yanping Jin ◽  
...  
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Raman Spectra ◽  
Infrared And Raman Spectra ◽  
Vibrational Assignment

FT-IR, FT-Raman spectra and ab initio HF and DFT calculations of 4-N,N′-dimethylamino pyridine

2008 ◽  
Vol 71 (3) ◽  
pp. 898-906 ◽  
Author(s):  
N. Sundaraganesan ◽  
S. Kalaichelvan ◽  
C. Meganathan ◽  
B. Dominic Joshua ◽  
J. Cornard
Keyword(s):  
Dft Calculations ◽  
Ab Initio ◽  
Raman Spectra ◽  
Ft Ir ◽  
Hf And Dft Calculations ◽  
Ab Initio Hf ◽  
Ft Raman

Molecular polarizability and polarizability derivatives in cyclohexane analyzed with the theory of atoms in molecules

1994 ◽  
Vol 98 (3) ◽  
pp. 771-776 ◽  
Author(s):  
Kathlene M. Gough ◽  
Hemant K. Srivastava ◽  
Katarina Belohorcova
Keyword(s):  
Atoms In Molecules ◽  
Molecular Polarizability
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