Effect and Characterization of Stone–Wales Defects on Graphene Quantum Dot: A First-Principles Study

A first principles based density functional theory (DFT) has been employed to identify the signature of Stone–Wales (SW) defects in semiconducting graphene quantum dot (GQD). Results show that the G mode in the Raman spectra of GQD has been red shifted to 1544.21 cm − 1 in the presence of 2.08% SW defect concentration. In addition, the intensity ratio between a robust low intense contraction–elongation mode and G mode is found to be reduced for the defected structure. We have also observed a Raman mode at 1674.04 cm − 1 due to the solo contribution of the defected bond. The increase in defect concentration, however, reduces the stability of the structures. As a consequence, the systems undergo structural buckling due to the presence of SW defect generated additional stresses. We have further explored that the 1615.45 cm − 1 Raman mode and 1619.29 cm − 1 infra-red mode are due to the collective stretching of two distinct SW defects separated at a distance 7.98 Å. Therefore, this is the smallest separation between the SW defects for their distinct existence. The pristine structure possesses maximum electrical conductivity and the same reduces to 0.37 times for 2.08% SW defect. On the other hand, the work function is reduced in the presence of defects except for the structure with SW defects separated at 7.98 Å. All these results will serve as an important reference to facilitate the potential applications of GQD based nano-devices with inherent topological SW defects.

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Thermodynamic Stability of Hexagonal and Rhombohedral Bn at Cvd Conditions from Van der Waals Corrected First Principles Calculations

10.26434/chemrxiv.8052218.v3 ◽

2019 ◽

Author(s):

Henrik Pedersen ◽

Björn Alling ◽

Hans Högberg ◽

Annop Ektarawong

Keyword(s):

Thin Films ◽

Thermodynamic Stability ◽

First Principles ◽

Thermal Equilibrium ◽

Density Functional ◽

Van Der Waals ◽

Chemical Vapor ◽

First Principles Calculations ◽

Functional Theory ◽

The Stability

Thin films of boron nitride (BN), particularly the sp<sup>2</sup>-hybridized polytypes hexagonal BN (h-BN) and rhombohedral BN (r-BN) are interesting for several electronic applications given band gaps in the UV. They are typically deposited close to thermal equilibrium by chemical vapor deposition (CVD) at temperatures and pressures in the regions 1400-1800 K and 1000-10000 Pa, respectively. In this letter, we use van der Waals corrected density functional theory and thermodynamic stability calculations to determine the stability of r-BN and compare it to that of h-BN as well as to cubic BN and wurtzitic BN. We find that r-BN is the stable sp<sup>2</sup>-hybridized phase at CVD conditions, while h-BN is metastable. Thus, our calculations suggest that thin films of h-BN must be deposited far from thermal equilibrium.

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Site preference and atomic ordering in the ternary Rh5Ga2As: first-principles calculations

Zeitschrift für Kristallographie - Crystalline Materials ◽

10.1515/zkri-2021-2019 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Nilanjan Roy ◽

Sucharita Giri ◽

Harshit ◽

Partha P. Jana

Keyword(s):

Total Energy ◽

First Principles ◽

Density Functional ◽

Structure Type ◽

Site Preference ◽

X Ray Diffraction ◽

Atomic Ordering ◽

Functional Theory ◽

The Stability ◽

Bonding Characteristics

Abstract The site preference and atomic ordering of the ternary Rh5Ga2As have been investigated using first-principles density functional theory (DFT). An interesting atomic ordering of two neighboring elements Ga and As reported in the structure of Rh5Ga2As by X-ray diffraction data only is confirmed by first-principles total-energy calculations. The previously reported experimental model with Ga/As ordering is indeed the most stable in the structure of Rh5Ga2As. The calculation detected that there is an obvious trend concerning the influence of the heteroatomic Rh–Ga/As contacts on the calculated total energy. Interestingly, the orderly distribution of As and Ga that is found in the binary GaAs (Zinc-blende structure type), retained to ternary Rh5Ga2As. The density of states (DOS) and Crystal Orbital Hamiltonian Population (COHP) are calculated to enlighten the stability and bonding characteristics in the structure of Rh5Ga2As. The bonding analysis also confirms that Rh–Ga/As short contacts are the major driving force towards the overall stability of the compound.

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The stability and electronic and photocatalytic properties of the ZnWO4 (010) surface determined from first-principles and thermodynamic calculations

RSC Advances ◽

10.1039/d1ra03218f ◽

2021 ◽

Vol 11 (38) ◽

pp. 23477-23490

Author(s):

Yonggang Wu ◽

Jihua Zhang ◽

Bingwei Long ◽

Hong Zhang

Keyword(s):

Phase Diagram ◽

Density Functional Theory ◽

First Principles ◽

Density Functional ◽

Thermodynamic Calculations ◽

Photocatalytic Properties ◽

Thermodynamic Approach ◽

Functional Theory ◽

Stability Phase Diagram ◽

The Stability

The ZnWO4 (010) surface termination stability is studied using a density functional theory-based thermodynamic approach. The stability phase diagram shows that O-Zn, DL-W, and DL-Zn terminations of ZnWO4 (010) can be stabilized.

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First-Principles Study of Triangle Terarylene as a Possible Optical Molecular Switch

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.311-313.526 ◽

2011 ◽

Vol 311-313 ◽

pp. 526-529

Author(s):

Cai Juan Xia ◽

Han Chen Liu ◽

Ji Xin Yin

Keyword(s):

First Principles ◽

Density Functional ◽

Molecular Switch ◽

Optical Switches ◽

Functional Theory ◽

Closed Ring ◽

Potential Applications ◽

Homo Lumo ◽

Non Equilibrium Green’S Function ◽

Theoretical Results

Using non-equilibrium Green’s function formalism combined with first-principles density functional theory, we investigate the electronic transport properties of a triangle terarylene(open- and closed-ring forms) optical molecular switch. The influence of the HOMO-LUMO gaps and the spatial distributions of molecular orbitals on the quantum transport through the molecular device is discussed. Theoretical results show that the conductance of the closed-ring is 3-8 times larger than that of open-ring, which expect that this system can be one of good candidates for optical switches due to this unique advantage, and may have some potential applications in future molecular circuit.

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The tuning effect of the electric field on the physical properties of some typical wurtzite semiconductors

Modern Physics Letters B ◽

10.1142/s0217984917503109 ◽

2017 ◽

Vol 31 (33) ◽

pp. 1750310 ◽

Cited By ~ 1

Author(s):

Jia-Ning Li ◽

San-Lue Hu ◽

Hao-Yu Dong ◽

Xiao-Ying Xu ◽

Jia-Fu Wang ◽

...

Keyword(s):

Electric Field ◽

Physical Properties ◽

First Principles ◽

Electronic Structures ◽

Density Functional ◽

Great Influence ◽

Semiconductor Materials ◽

Functional Theory ◽

The Stability ◽

Wurtzite Semiconductors

Under the tuning of an external electric field, the variation of the geometric structures and the band gaps of the wurtzite semiconductors ZnS, ZnO, BeO, AlN, SiC and GaN have been investigated by the first-principles method based on density functional theory. The stability, density of states, band structures and the charge distribution have been analyzed under the electric field along (001) and (00[Formula: see text]) directions. Furthermore, the corresponding results have been compared without the electric field. According to our calculation, we find that the magnitude and the direction of the electric field have a great influence on the electronic structures of the wurtzite materials we mentioned above, which induce a phase transition from semiconductor to metal under a certain electric field. Therefore, we can regulate their physical properties of this type of semiconductor materials by tuning the magnitude and the direction of the electric field.

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The effect of Ru on Ti50Pd50 high temperature shape memory alloy: a first-principles study

MRS Advances ◽

10.1557/adv.2019.331 ◽

2019 ◽

Vol 4 (44-45) ◽

pp. 2419-2429 ◽

Cited By ~ 1

Author(s):

R. G. Diale ◽

R. Modiba ◽

P. E. Ngoepe ◽

H. R. Chauke

Keyword(s):

First Principles ◽

Density Functional ◽

Lattice Parameter ◽

Heat Of Formation ◽

Partial Substitution ◽

Martensitic Transformation Temperature ◽

Functional Theory ◽

Equilibrium Lattice Parameter ◽

Strengthening Element ◽

The Stability

ABSTRACTThe stability of the Ti50Pd50-xRux alloy was investigated using first-principles density functional theory within the plane-wave pseudopotential method. Firstly, the Ti50Pd50 gave equilibrium lattice parameter and lowest heats of formation in better agreement with experimental data to within 3%. The heat of formation decreases with an increase in Ru concentration, consistent with the trend of the density of states which is lowered at the Fermi level as Ru content is increased which suggests stability. It was also found that from the calculated elastic constants the structures showed positive shear modulus above 20 at. % Ru, condition of stability. Furthermore, the addition of Ru was found to strengthen the Ti50Pd50-xRux system at higher concentrations. The thermal coefficients of linear expansion for the Ti50Pd31.25Ru18. 75 are higher at low temperature, and that the TiPd-Ru system tends to expand more at low content of 18.75 at. % Ru than at higher content. Partial substitution of Pd with Ru was found more effective as a strengthening element and may enhance the martensitic transformation temperature of the Ti50Pd50 alloy.

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Catalytic performance of graphene quantum dot supported manganese phthalocyanine for efficient oxygen reduction: density functional theory approach

New Journal of Chemistry ◽

10.1039/c8nj05093g ◽

2019 ◽

Vol 43 (1) ◽

pp. 348-355 ◽

Cited By ~ 10

Author(s):

Nguyet N. T. Pham ◽

Jong S. Park ◽

Hee-Tak Kim ◽

Hyoung-Juhn Kim ◽

Young-A Son ◽

...

Keyword(s):

Density Functional Theory ◽

Free Energy ◽

Quantum Dot ◽

Oxygen Reduction ◽

Density Functional ◽

Catalytic Performance ◽

Theory Approach ◽

Functional Theory ◽

Graphene Quantum Dot ◽

Orr Activity

The thermodynamic free-energy diagrams predict that MnPc/GQD is more active toward ORR than the isolated MnPc, clearly highlighting the effect of the GQD matrix on ORR activity from a thermodynamic perspective.

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DFT calculations of the structure and stability of copper clusters on MoS2

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.11.30 ◽

2020 ◽

Vol 11 ◽

pp. 391-406

Author(s):

Cara-Lena Nies ◽

Michael Nolan

Keyword(s):

First Principles ◽

Density Functional ◽

Noble Metals ◽

Semiconductor Device ◽

2D Materials ◽

Single Atom ◽

Copper Binding ◽

Adsorption Sites ◽

Potential Applications ◽

Low Dimensional

Layered materials, such as MoS2, are being intensely studied due to their interesting properties and wide variety of potential applications. These materials are also interesting as supports for low-dimensional metals for catalysis, while recent work has shown increased interest in using 2D materials in the electronics industry as a Cu diffusion barrier in semiconductor device interconnects. The interaction between different metal structures and MoS2 monolayers is therefore of significant importance and first-principles simulations can probe aspects of this interaction not easily accessible to experiment. Previous theoretical studies have focused particularly on the adsorption of a range of metallic elements, including first-row transition metals, as well as Ag and Au. However, most studies have examined single-atom adsorption or adsorbed nanoparticles of noble metals. This means there is a knowledge gap in terms of thin film nucleation on 2D materials. To begin addressing this issue, we present in this paper a first-principles density functional theory (DFT) study of the adsorption of small Cu n (n = 1–4) structures on 2D MoS2 as a model system. We find on a perfect MoS2 monolayer that a single Cu atom prefers an adsorption site above the Mo atom. With increasing nanocluster size the nanocluster binds more strongly when Cu atoms adsorb atop the S atoms. Stability is driven by the number of Cu–Cu interactions and the distance between adsorption sites, with no obvious preference towards 2D or 3D structures. The introduction of a single S vacancy in the monolayer enhances the copper binding energy, although some Cu n nanoclusters are actually unstable. The effect of the vacancy is localised around the vacancy site. Finally, on both the pristine and the defective MoS2 monolayer, the density-of-states analysis shows that the adsorption of Cu introduces new electronic states as a result of partial Cu oxidation, but the metallic character of Cu nanoclusters is preserved.

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Designing an efficient graphene quantum dot-filled luminescent down shifting layer to improve the stability and efficiency of perovskite solar cells by simple optical modeling

RSC Advances ◽

10.1039/c8ra06196c ◽

2018 ◽

Vol 8 (55) ◽

pp. 31502-31509 ◽

Cited By ~ 8

Author(s):

Zahra Hosseini ◽

Teymoor Ghanbari

Keyword(s):

Solar Cells ◽

Solar Cell ◽

Quantum Dot ◽

Perovskite Solar Cells ◽

Perovskite Solar Cell ◽

Luminescent Material ◽

Suitable Candidate ◽

Graphene Quantum Dot ◽

Optical Modeling ◽

The Stability

Optical modeling of a GQD-filled LDS layer on top of a perovskite solar cell (PSC) confirms GQDs as a suitable candidate as a luminescent material for application of the LDS strategy in PSCs.

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First Principles Modelling of Scroll-to-Nanotube Defect: Screw-Type Dislocation

Materials Science Forum ◽

10.4028/www.scientific.net/msf.527-529.1583 ◽

2006 ◽

Vol 527-529 ◽

pp. 1583-1586 ◽

Cited By ~ 1

Author(s):

I. Suarez-Martinez ◽

G. Savini ◽

M.I. Heggie

Keyword(s):

First Principles ◽

Density Functional ◽

Wide Band ◽

Interlayer Spacing ◽

Density Functional Theory Study ◽

Wide Band Gap ◽

Functional Theory ◽

Potential Applications ◽

Wide Band Gap Semiconductors ◽

Type Dislocation

Carbon nanotubes present interesting potential applications especially in nanoelectronics. Their electrical properties are known to be a function of their chirality. It happens that 1/3 of CNs are metallic and 2/3 are semiconductors. Narrow nanotubes are expected to be wide-band gap semiconductors. Several experimental results have shown that the thickness of a multi-wall nanotube along the axis can change, while the interlayer spacing remains fairly constant. These observations suggest the coexistence in the same tube of a scroll structure and a multi-wall nested tube. We explain this defect as a screw dislocation which by gliding transforms between these two forms. In this paper, we present a density functional theory study of the structure and energetics of screw dislocations in AA and ABC graphite, and we discuss their role in the scroll-to-nanotube transformation in multi-wall nanotubes.

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