Vibrational properties of nanographene

Singh, Sandeep Kumar; Peeters, F. M.

doi:10.2478/nsmmt-2013-0002

Cited by 5 publications

(6 citation statements)

References 36 publications

(45 reference statements)

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“…On the other hand, the changes observed in the low-frequency part can be expectedly connected with the appearance of the sp 2 C-H deformational vibrations of different types (see Table 1). In contrast to a previous conclusion [21], the addition of hydrogen atoms on the domain edges deviated the DOV rather significantly. Trendlines plotted in the figure are quite convenient for demonstration of general patterns, but are not very accurate at presenting the detailed difference of the two vibrational spectra.…”

Section: Necklaced Graphene Hydridescontrasting

confidence: 99%

“…As shown by the DOV trendline, the vibration spectrum was clearly divided into two parts from 20 to 1100 cm −1 and from 1100 to 1800 cm −1 , respectively. This two-part character of the vibration spectrum of NGMs also remained in the crystalline state [21,26,27].…”

Section: General Frequency Kits Of Bare Graphene Domainsmentioning

confidence: 75%

“…These were NGMs based on the only (5,5) 1 and 2. 1 Greek symbols  and  mark the molecule bending and stretching, respectively; 2 Equilibrated structures, AM1 UHF calculations; 3 Reference is taken from [20]; frequency regions are given in the experimental spectra scale; 4 Out-of-plane deformations; 5 In plane deformations; 6 Collective vibrations of the graphene domain atoms [21].…”

Section: Digital Twins → Virtual Device → It Productmentioning

confidence: 99%

“…ages 2 SPECTRAL REGIONS ence 3 300-1000 1000-1200 1200-1300 1300-1500 1500-1600 1600-1700 1800-1900 2600-3000 3000-3600 op 4 , ip 1 Greek symbols δ and ν mark the molecule bending and stretching, respectively; 2 Equilibrated structures, AM1 UHF calculations; 3 Reference is taken from [20]; frequency regions are given in the experimental spectra scale; 4 Out-of-plane deformations; 5 In plane deformations; 6 Collective vibrations of the graphene domain atoms [21]. 1 Greek symbols  and  mark the molecule bending and stretching, respectively; 2 Equilibrated structures, AM1 UHF calculations; 3 Reference is taken from [20]; frequency regions are given in the experimental spectra scale; 4 Out-of-plane deformations; 5 In plane deformations; 6 Collective vibrations of the graphene domain atoms [21]. 1 Blod GFKs correspond to the most intense bands; 2 Equilibrated structures, AM1 UHF calculations; 3 Authors' suggestions on the basis of original studies [19,[22][23][24]; frequency regions are given in the experimental spectra scale; 4 Out-of-plane deformations; 5 In plane deformations.…”

Section: Digital Twins → Virtual Device → It Productmentioning

confidence: 99%

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Virtual Vibrational Analytics of Reduced Graphene Oxide

Sheka

Popova

2022

IJMS

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The digital twin concept lays the foundation of the virtual vibrational analytics suggested in the current paper. The latter presents extended virtual experiments aimed at determining the specific features of the optical spectra of the studied molecules that provide reliable express analysis of the body spatial structure and chemical content. Reduced graphene oxide was selected as the virtual experiment goal. A set of nanosize necklaced graphene molecules, based on the same graphene domain but differing by the necklace contents, were selected as the relevant DTs. As shown, the Raman spectra signatures contained information concerning the spatial structure of the graphene domains, while the molecule necklaces were responsible for the IR spectra. Suggested sets of general frequency kits facilitate the detailed chemical analysis. Express analysis of a shungite carbon, composed of rGO basic structural units, revealed the high ability of the approach.

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Section: Necklaced Graphene Hydridescontrasting

confidence: 99%

Section: General Frequency Kits Of Bare Graphene Domainsmentioning

confidence: 75%

Section: Digital Twins → Virtual Device → It Productmentioning

confidence: 99%

Section: Digital Twins → Virtual Device → It Productmentioning

confidence: 99%

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Virtual Vibrational Analytics of Reduced Graphene Oxide

Sheka

Popova

2022

IJMS

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“…6 Benzene molecule data [ 56 ]. 7 Virtual data for nanographene [ 57 ]. 8 The author approximated suggestions for GO.…”

Section: Figurementioning

confidence: 99%

Digital Twins Solve the Mystery of Raman Spectra of Parental and Reduced Graphene Oxides

Sheka

2022

Nanomaterials

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Digital Twins concept presents a new trend in virtual material science, common to all computational techniques. Digital twins, virtual devices and intellectual products, presenting the main constituents of the concept, are considered in detail on the example of a complex problem, which concerns an amazing identity of the D-G-doublet Raman spectra of parental and reduced graphene oxides. Digital twins, presenting different aspects of the GO and rGO structure and properties, were virtually synthesized using a spin-density algorithm emerging from the Hartree-Fock approximation. Virtual device presents AM1 version of the semi-empirical unrestricted HF approximation. The equilibrium structure of the twins as well as virtual one-phonon harmonic spectra of IR absorption and Raman scattering constitute a set of intellectual products. It was established that in both cases the D-G doublets owe their origin to the sp3 and sp2 C-C stretchings, respectively. This outwardly similar community reveals different grounds. Thus, multilayer packing of individual rGO molecules in stacks provides the existence of the sp3 D band in addition to sp2 G one. The latter is related to stretchings of the main pool of sp2 C-C bonds, while the sp3 constituent presents out-of-plane stretchings of dynamically stimulated interlayer bonds. In the GO case, the sp3 D component, corresponding to stretchings of the main pool of sp3 C-C bonds, is accompanied by an sp2 G component, which is related to stretchings of the remaining sp2 C-C bonds provided with the spin-influenced prohibition of the 100% oxidative reaction in graphene domain basal plane.

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Electronic structure and aromaticity of large-scale hexagonal graphene nanoflakes

Lin

Yang

et al. 2014

The Journal of Chemical Physics

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With the help of the recently developed SIESTA-PEXSI method [J. Phys.: Condens. Matter 26, 305503 (2014)], we perform Kohn-Sham density functional theory (DFT) calculations to study the stability and electronic structure of hexagonal graphene nanoflakes (GNFs) with up to 11,700 atoms. We find the electronic properties of GNFs, including their cohesive energy, HOMO-LUMO energy gap, edge states and aromaticity, depend sensitively on the type of edges (ACGNFs and ZZGNFs), size and the number of electrons. We observe that, due to the edge-induced strain effect in ACGNFs, large-scale ACGNFs' cohesive energy decreases as their size increases. This trend does not hold for ZZGNFs due to the presence of many edge states in ZZGNFs. We find that the energy gaps Eg of GNFs all decay with respect to 1/L, where L is the size of the GNF, in a linear fashion. But as their size increases, ZZGNFs exhibit more localized edge states. We believe the presence of these states makes their gap decrease more rapidly. In particular, when L is larger than 6.40 nm, we find that ZZGNFs exhibit metallic characteristics. Furthermore, we find that the aromatic structures of GNFs appear to depend only on whether the system has 4N or 4N + 2 electrons, where N is an integer.

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Vibrational properties of nanographene

Cited by 5 publications

References 36 publications

Virtual Vibrational Analytics of Reduced Graphene Oxide

Virtual Vibrational Analytics of Reduced Graphene Oxide

Digital Twins Solve the Mystery of Raman Spectra of Parental and Reduced Graphene Oxides

Electronic structure and aromaticity of large-scale hexagonal graphene nanoflakes

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