Density Functional Theoretical Analysis of the Molecular Structural Effects on Raman Spectra ofβ-Carotene and Lycopene

2012 ◽  
Vol 30 (10) ◽  
pp. 2573-2580 ◽  
Author(s):  
Weilong Liu ◽  
Zhigang Wang ◽  
Zhiren Zheng ◽  
Lilin Jiang ◽  
Yanqiang Yang ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Raman Spectra ◽  
Density Functional ◽  
Structural Effects

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.

Molecular Vibration Theoretical Analysis of Two-Dimensional Photoelectric Conversion Material WSe2

2018 ◽  
Vol 765 ◽  
pp. 16-23
Author(s):  
Rui Zhang ◽  
Hong Bo Li ◽  
Guo Qiang Hao ◽  
Wen Bo Liu ◽  
Xiao Jun Ye ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Density Functional ◽  
Molecular Vibration ◽  
Raman Shift ◽  
Vibration Modes ◽  
Photoelectric Conversion ◽  
Functional Theory ◽  
Conversion Materials ◽  
Direct Band ◽  
New Generation

Monolayer WSe2is flexible, nearly transparent and direct band-gap semiconductor with the potential to be new generation thin film photoelectric conversion materials. The molecule vibration modes of monolayer and bulk WSe2was analyzed by factor group and the phonons dispersion and vibration frequency was calculated by first-principles based on density functional theory. Furthermore, the comparison between the above calculations and experiment values of Raman shift of monolayer and bulk WSe2was made to verify the accuracy of theoretical analysis and theoretically explain the differences of monolayer and bulk WSe2materials in Raman spectra.

scholarly journals C2: An Asymmetric Specie ?

2020 ◽  
Author(s):  
Robson de Farias
Keyword(s):  
Chemical Bond ◽  
Raman Spectra ◽  
Density Functional ◽  
Functional Approach ◽  
Ir And Raman Spectra ◽  
Basis Set ◽  
Ir And Raman

<p> The present work is another contribution to a better understanding of the chemical bond in C<sub>2</sub>. Several density functional approach/basis set provided calculated IR and Raman spectra with simultaneous active bands. Hence, the hypothesis of electronic asymmetry in C<sub>2</sub> [1] was reinforced. </p>

Electronic properties of N-rich graphene nano-chevrons.

2021 ◽  
Author(s):  
Anderson Soares da Costa Azevêdo ◽  
Aldilene Saraiva-Souza ◽  
Vincent Meunier ◽  
Eduardo Costa Girão
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
Theoretical Analysis ◽  
Electronic Properties ◽  
Density Functional ◽  
Functional Theory ◽  
Nitrogen Doped ◽  
Electronic And Magnetic Properties ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

Theoretical analysis based on density functional theory is used to describe the microscopic origins of emerging electronic and magnetic properties in quasi-1D nitrogen-doped graphene nanoribbon structures with chevron-like (or wiggly-edged)...

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