scholarly journals The Flexible Lubrication Performance of Graphene Used in Diamond Interface as a Solid Lubricant: First-Principles Calculations

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1784
Author(s):  
Jianjun Wang ◽  
Lin Li ◽  
Wentao Yang ◽  
Meng Li ◽  
Peng Guo ◽  
...  
Keyword(s):  
Diamond Film ◽  
First Principles ◽  
Density Functional ◽  
External Pressure ◽  
Diamond Surface ◽  
Interfacial Friction ◽  
First Principles Calculations ◽  
Diamond Surfaces ◽  
Lubrication Performance ◽  
Wide Range

The interfacial friction performances of graphene covered and hydrogen-terminated diamond surfaces were investigated comparatively by first-principles calculations within density functional theory (DFT). Both systems exhibit similar excellent lubricating effects under small load, but the graphene covered interface presents small friction than that of hydrogenated system for the larger load. The calculated interfacial friction between two sheets of graphene covered diamond surface increases slowly than that of hydrogenated system in a wide range of pressure scale, and the friction difference between the two systems increases with increasing external pressure, indicating that graphene has flexible lubricating properties with high load-carrying capacity. This behavior can be attributed to the large interlayer space and a more uniform interlayer charge distribution of graphene covered diamond interface. Our investigations suggest that graphene is a promising candidate as solid lubricate used in diamond film, and are helpful for the understanding of interfacial friction properties of diamond film.

Surface stability and electronic structure of hydrogen- and fluorine-terminated diamond surfaces: A first-principles investigation

2009 ◽  
Vol 24 (8) ◽  
pp. 2461-2470 ◽  
Author(s):  
Fatih G. Sen ◽  
Yue Qi ◽  
Ahmet T. Alpas
Keyword(s):  
First Principles ◽  
Negative Charge ◽  
Close Packing ◽  
Diamond Surface ◽  
First Principles Calculations ◽  
Surface Phase ◽  
Surface Stability ◽  
Diamond Surfaces ◽  
Bonding Structure ◽  
The Stability

The effect of fluorine termination on the stability and bonding structure of diamond (111) surfaces were studied using first-principles calculations and compared with hydrogen termination by creating mixed F- and H-containing diamond surfaces. Surface F atoms, similar to H, formed sp3-type bonding with C atoms, which resulted in a more stable 1 × 1 configuration. The surface phase diagram built showed that the F-terminated surface was more stable in a larger-phase space than H termination, because of the formation of strong ionic C–F bonds and the development of attractive forces between F atoms, resulting in close packing of large F atoms. Hence, the F-terminated diamond surface was more chemically inert. A large repulsive force was required to bring two F-terminated surfaces together, because of the negative charge on F atoms, resulting in reduced adhesion tendency between two F-terminated diamond surfaces compared with H-terminated surfaces.

scholarly journals First-principles calculations of LiNbO3 optical properties: From far-infrared to ultraviolet

2018 ◽  
Vol 32 (05) ◽  
pp. 1850063 ◽  
Author(s):  
Vladimir Saleev ◽  
Alexandra Shipilova
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Atomic Orbital ◽  
Hybrid Approach ◽  
Far Infrared ◽  
Basis Sets ◽  
Dielectric Tensor ◽  
First Principles Calculations ◽  
Wide Range

We perform first-principles calculations of optical properties for ferroelectric phase of LiNbO3 crystal using density functional theory (DFT) for wide range of wavelengths, from far-infrared (IR) to ultraviolet. We study frequency dependence of complex dielectric tensor and related quantities, such as refractive and reflection indices, absorption coefficients, etc. Our calculation incorporates advantages of numerical approaches based on atomic-orbital all-electron Gaussian-type basis sets, as it is realized in CRYSTAL14 program. We compared predictions obtained in general-gradient approach with PBESOL exchange-correlation functional and in hybrid approach with PBESOL0 functional, and we have found that hybrid PBESOL0 functional is more applicable to describe the wide set of the experimental data.

Correction methods for first-principles calculations of the solution enthalpy of gases and compounds in liquid metals

2021 ◽  
Author(s):  
Junhyoung Gil ◽  
Takuji Oda
Keyword(s):  
Flexible Electronics ◽  
First Principles ◽  
Density Functional ◽  
Liquid Metals ◽  
First Principles Calculations ◽  
Calculation Methods ◽  
Accurate Calculation ◽  
Functional Theory ◽  
Solution Enthalpy ◽  
Wide Range

Liquid metals (LMs) have a wide range of engineering applications, such as in coolants, batteries, and flexible electronics. While accurate calculation methods for thermodynamic properties based on density functional theory...

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

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.

scholarly journals Hydrogenation and oxidation enhances the thermoelectric performance of Si2BN monolayer

2021 ◽  
Author(s):  
H. R. Mahida ◽  
Deobrat Singh ◽  
Yogesh Sonvane ◽  
Sanjeev K. Gupta ◽  
P. B. Thakor ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Charge Transport ◽  
Transport Properties ◽  
First Principles ◽  
Density Functional ◽  
Thermoelectric Performance ◽  
First Principles Calculations ◽  
Functional Theory

In the present study, we have investigated the structural, electronic, and charge transport properties of pristine, hydrogenated, and oxidized Si2BN monolayers via first-principles calculations based on density functional theory (DFT).

Structural, elastic and thermodynamic properties of A15-type compounds V3X (X = Ir, Pt and Au) from first-principles calculations

2016 ◽  
Vol 30 (35) ◽  
pp. 1650414 ◽  
Author(s):  
Mingliang Wang ◽  
Zhe Chen ◽  
Dong Chen ◽  
Cunjuan Xia ◽  
Yi Wu
Keyword(s):  
Thermodynamic Properties ◽  
Debye Temperature ◽  
First Principles ◽  
Density Functional ◽  
Coefficient Of Thermal Expansion ◽  
Local Density ◽  
Debye Model ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Experimental Values

The structural, elastic and thermodynamic properties of the A15 structure V3Ir, V3Pt and V3Au were studied using first-principles calculations based on the density functional theory (DFT) within generalized gradient approximation (GGA) and local density approximation (LDA) methods. The results have shown that both GGA and LDA methods can process the structural optimization in good agreement with the available experimental parameters in the compounds. Furthermore, the elastic properties and Debye temperatures estimated by LDA method are typically larger than the GGA methods. However, the GGA methods can make better prediction with the experimental values of Debye temperature in V3Ir, V3Pt and V3Au, signifying the precision of the calculating work. Based on the E–V data derived from the GGA method, the variations of the Debye temperature, coefficient of thermal expansion and heat capacity under pressure ranging from 0 GPa to 50 GPa and at temperature ranging from 0 K to 1500 K were obtained and analyzed for all compounds using the quasi-harmonic Debye model.

Probing the electronic structures of Con (n = 1–5) clusters on γ-Al2O3 surfaces using first-principles calculations

2017 ◽  
Vol 19 (5) ◽  
pp. 3679-3687 ◽  
Author(s):  
Tao Yang ◽  
Masahiro Ehara
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
First Principles Calculations ◽  
Functional Theory

Using density functional theory calculations, we discussed the geometric and electronic structures and nucleation of small Co clusters on γ-Al2O3(100) and γ-Al2O3(110) surfaces.

Stability and Structures of Constitutional Defects in Nonstoichiometric Intermetallic Compounds by First-Principles Calculations

2005 ◽  
Vol 475-479 ◽  
pp. 3111-3114
Author(s):  
Masataka Mizuno ◽  
Hideki Araki ◽  
Yasuharu Shirai
Keyword(s):  
Intermetallic Compounds ◽  
First Principles ◽  
Electronic Structures ◽  
Stoichiometric Composition ◽  
Electronic Structure Calculations ◽  
First Principles Calculations ◽  
Compositional Dependence ◽  
Wide Range ◽  
Formation Energies ◽  
Structure Calculations

Some of intermetallic compounds exist in a wide range of concentration around the stoichiometric composition. First-principles electronic structure calculations have been performed for constitutional defects in non-stoichiometric CoAl and CoTi in order to investigate their stabilities and structural relaxations induced by constitutional defects. For the evaluation of stabilities of constitutional defects, the compositional dependence curves both of formation energies and of lattice parameters are obtained by the calculations employing supercells in various sizes. The lattice relaxations around constitutional defects are discussed by analyzing the change in electronic structures induced by constitutional defects.

First-Principles Studies of the Magnetic Properties of hcp Cr in Cr/Cu(111) and Cr/Ru(0001) Superlattices

2002 ◽  
Vol 721 ◽  
Author(s):  
G. Y. Guo
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Recent Observation ◽  
Theoretical Calculations ◽  
Ferromagnetic State ◽  
Full Potential ◽  
Generalized Gradient ◽  
Plane Wave Method ◽  
Wide Range ◽  
Linearized Augmented Plane Wave

AbstractLatest first-principles density functional theoretical calculations using the generalized gradient approximation and highly accurate all-eleectron full-potential linearized augmented plane wave method, show that bulk hcp Cr would be a paramagnet and that no ferromagnetic state could be stabilized over a wide range of volume [1]. To understand the recent observation of the weakly ferromagnetic state of Cr in hcp Cr/Ru (0001) superlattices [2], the same theoretical calculations have been carried out for the hcp Cr3/Ru7 (0001) and hcp Cr3/fcc Cu6 (111) superlattices. The Cr/Ru superlattice is found to be ferromagnetic with a small magnetic moment of ∼0.31μB/Cr while in contrast, Cr/Cu superlattice is found to be nonmagnetic.

Electronic structure of cubic BaTbO3 from first-principles pseudopotential calculations

2006 ◽  
Vol 84 (2) ◽  
pp. 115-120 ◽  
Author(s):  
G Y Gao ◽  
K L Yao ◽  
Z L Liu
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Pseudopotential Calculations ◽  
Correlation Potential ◽  
Density Contour

First-principles calculations of the electronic structure are performed for cubic BaTbO3 using the plane-wave pseudopotential method within the framework of density functional theory and using the generalized gradient approximation for the exchange-correlation potential. Our calculations show that cubic BaTbO3 is metallic, and that this metallic character is mainly governed by the Tb 4f electrons and the hybridization between the Tb 5d and O 2p states. From the analysis of the density of states, band structure, and charge density contour, we find that the chemical bonding between Tb and O is covalent while that between Ba and TbO3 is ionic. PACS Nos.: 71.15.Mb, 71.20.-b

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