FIRST-PRINCIPLES INVESTIGATION OF THE ELECTRONIC, ELASTIC AND THERMODYNAMIC PROPERTIES OF SUPERCONDUCTING MgB2

2014 ◽  
Vol 28 (10) ◽  
pp. 1450057 ◽  
Author(s):  
HONGYING LU ◽  
JIANPING LONG ◽  
LIJUN YANG ◽  
WEN HUANG
Keyword(s):  
Thermal Conductivity ◽  
Sound Velocity ◽  
Debye Temperature ◽  
First Principles ◽  
Function Theory ◽  
Density Function Theory ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Anisotropy Index ◽  
Longitudinal Sound Velocity

The electronic structure, elastic properties, Debye temperature and thermal conductivity of MgB 2 are investigated by using the first-principles density function theory within the generalized gradient approximation (GGA). The calculated elastic constants indicate that the MgB 2 is mechanically stable. The shear modulus, Young's modulus, Poisson's ratio, σ, the ratio B/G and universal anisotropy index are also calculated. Finally, the averaged sound velocity, longitudinal sound velocity, transverse sound velocity, Debye temperature and thermal conductivity are obtained.

First Principles Calculation on Adsorption of S on Impurity Fe (100)

2012 ◽  
Vol 472-475 ◽  
pp. 1538-1543
Author(s):  
Qiang Luo ◽  
Zhi Zhang ◽  
Qiang Zhang ◽  
Tai He Shi ◽  
Zeng Ling Ran
Keyword(s):  
Electronic Properties ◽  
Density Function ◽  
Molecular Orbital ◽  
Adsorption Energy ◽  
First Principles ◽  
Function Theory ◽  
Density Function Theory ◽  
First Principles Calculation ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation

Using the first principles method, which is based on the density function theory (DFT), the structures and electronic properties of S atoms are adsorbed on the Fe (100) surface for X(X is Cr, Ni, Mo, C, Mn ,Si,P and S) impurities in Fe, and their molecular orbital and absorption energies were calculated with the generalized gradient approximation. The results show that S adsorbed on H site for Cr, Ni, Mn, C and Mo impurities in Fe is stable but for Si, S and P is B site. The adsorption energy for Ni in impurity Fe is almost nearby for the purity Fe and the effect for Ni in S absorption on Fe (100) surface is very small. In order to prevent S absorption on Fe surface，we can reduce the percentage of Ni.

First Principles Study on Adsorption for Different Concentration of H2S on Fe(100)

2014 ◽  
Vol 1015 ◽  
pp. 521-525 ◽  
Author(s):  
Qiang Zhang ◽  
Ping Jun Hu ◽  
Qiang Luo ◽  
Yi Qiu ◽  
Zeng Ling Ran
Keyword(s):  
Density Of States ◽  
First Principles ◽  
Function Theory ◽  
Surface Adsorption ◽  
Density Function Theory ◽  
Partial Density ◽  
Total Density ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Total Density Of States

Using the first principles method, which is based on the density function theory (DFT), the structures and electronic properties for different concentration of H2S are adsorbed on the Fe (100) surface, and their molecular orbital and absorption energies were calculated with the generalized gradient approximation. The results show that, whether one or two molecules of H2S adsorpted Fe (100) surface, adsorption of single molecules Fe (100) surface partial density of states between pure Fe (100) and two molecules, and the total density of states is mainly composed of 3d electronic contribution.

Structural and Electronic Properties of Armchair GaN Nanoribbons with AlN Edges: First-Principles Study

2013 ◽  
Vol 771 ◽  
pp. 101-104
Author(s):  
Xiu Juan Du ◽  
Zheng Chen ◽  
Jing Zhang ◽  
Zhao Rong Ning
Keyword(s):  
Electronic Properties ◽  
First Principles ◽  
Function Theory ◽  
Density Function Theory ◽  
Band Gaps ◽  
Ribbon Width ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Structural And Electronic Properties ◽  
Projector Augmented Wave

Under the generalized gradient approximation (GGA), the structural and electronic properties of armchair GaN nanoribbons with AlN edges have been investigated by using the first-principles projector-augmented wave (PAW) potential within the density function theory (DFT) framework. The results reflect that the band gaps of the armchair GaN nanoribbons (AGaNNRs) are vibrated with the increasing ribbon width. For Al, Ga, H and N atom, the successively increasing electronegativity of 3.04, 2.1, 1.81 and 1.61 causes the successive increase of the charge density. These results are very useful for the applications of the AGaNNRs.

First Principles Calculation on Adsorption of S on Fe(100)

2011 ◽  
Vol 337 ◽  
pp. 690-694 ◽  
Author(s):  
Zhang Zhi ◽  
Qiang Luo ◽  
Zeng Ling Ran ◽  
Tai He Shi
Keyword(s):  
Density Of States ◽  
First Principles ◽  
Function Theory ◽  
Density Function Theory ◽  
Binding Energies ◽  
First Principles Calculation ◽  
Partial Density ◽  
Hollow Site ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation

Using the first principles method, which is based on the density function theory (DFT), the structures and electronic properties of S atoms are adsorbed on the Fe (100) surface, and their molecular orbital and binding energies were calculated with the generalized gradient approximation. The results show that the S atom is adsorbed hollow site is stable. With partial density of states, we have obtained the interaction of s and p states for S and Fe. It shows that the interaction between the S adsorption on the clean Fe (100) surface does lead to FeS comes into being.

First-Principles Calculation for Improving Room Temperature Ductility of B2-NiAl by Fe

2011 ◽  
Vol 327 ◽  
pp. 94-99
Author(s):  
Yu Xiang Lu ◽  
Guo Liang Qi ◽  
Liang Cheng
Keyword(s):  
First Principles ◽  
Room Temperature ◽  
Nearest Neighbor ◽  
Function Theory ◽  
Population Analysis ◽  
First Principles Calculation ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Room Temperature Ductility ◽  
The Impact

Generalized gradient approximation (GGA) of the density function theory (DFT) was applied to calculate many properties including density of states, population analysis and electron density in NiAl and NiAl(Fe) to investigate the mechanism of improving room temperature ductility of B2-NiAl by Fe. It was shown that the strong bond to Al p and Ni d hybridization, which leads to the embrittlement of B2-NiAl at room temperature. Addition of Fe, which is beneficial to improve ambient ductility of B2-NiAl, weakens the impact of the bond to Al p and Ni d hybridization and enhances the interaction among next-nearest-neighbor Ni atoms to make the charge distribution uniform along <100>.

First-principles investigation of the electronic, mechanical, and thermodynamic properties of europium carbide

2015 ◽  
Vol 93 (4) ◽  
pp. 409-412 ◽  
Author(s):  
Wen Huang ◽  
Lijun Yang
Keyword(s):  
Thermodynamic Properties ◽  
Shear Modulus ◽  
Sound Velocity ◽  
First Principles ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Longitudinal Sound Velocity ◽  
Temperature Melting

The electronic, mechanical, and thermodynamic properties of europium carbide (EuC2) are investigated using first-principles density functional theory within the generalized gradient approximation. The calculated elastic constants indicate that EuC2 is mechanically stable. The shear modulus, Young’s modulus, Poisson’s ratio, the bulk modulus – shear modulus ratio, shear anisotropy, and elastic anisotropy are also calculated. Finally, we obtain the Vickers hardness, averaged sound velocity, longitudinal sound velocity, transverse sound velocity, Debye temperature, melting point, and thermal conductivity of EuC2.

Density Functional Theory Applying in the Computation to the Properties of Copper Surface

2008 ◽  
Vol 575-578 ◽  
pp. 612-615
Author(s):  
Hong Tao Cheng ◽  
Jian Guo Yang ◽  
Hong Yuan Fang
Keyword(s):  
Density Functional ◽  
Function Theory ◽  
Local Density ◽  
Copper Surface ◽  
Density Function Theory ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
Experimental Values ◽  
Cohesive Energies

The properties of different Cu surface were studied by the pseudo-potentials method based on density function theory. The lattice constant obtained with GGA(Generalized Gradient Approximation) is close to the experimental values than that with LDA(Local Density Approximation), so we adopt the GGA to simulate the cohesive energies and the surface energies of the Cu(100), Cu(110) and Cu(111) surface. The simulated results are shown to be in agreement with the macroscopic validity of the experimental measurements.

scholarly journals Decomposition mechanism of dihydroxylammonium 5,5'-bis(tetrazole)-1,1'-diolate on Al(111) surface by periodic DFT calculation

2020 ◽  
Vol 85 (5) ◽  
pp. 651-660
Author(s):  
Ying Zhao ◽  
Xiaoling Xing ◽  
Shengxiang Zhao ◽  
Xuehai Ju
Keyword(s):  
Periodic Boundary ◽  
Dft Calculation ◽  
Function Theory ◽  
Periodic Boundary Conditions ◽  
Activation Energies ◽  
Density Function Theory ◽  
Generalized Gradient ◽  
Dft Methods ◽  
Generalized Gradient Approximation ◽  
Adsorption Energies

The generalized gradient approximation (GGA) of density function theory (DFT) methods are employed to investigate the decomposition of TKX- -50 molecule on the Al(111) surface. The calculation employs an Al supercell slab model and periodic boundary conditions. Five kinds of adsorption configurations for TKX-50 on Al surface are studied. The TKX-50 is adsorbed on Al surface to form the N?Al, O?Al and OH?Al bonds. The adsorption energies are in the range from ?113.15 to ?1334.40 kJ/mol. The activation energies of all configurations are in the range of 100.34?354.10 kJ/mol. The N1-N2 ruptures in V1 and N2-N3 ruptures in V2 takes place easily. The activation energies of these two bonds rupture (100.34 and 108.06 kJ/mol, respectively) are less than that of pure TKX-50 (161.58 and 215.99 kJ/mol). Al atoms promote the breaking of the tetrazole ring of TKX-50. The quantities of electron transfer from Al atoms to TKX-50 are in range of 1.42?4.90 e.

Effect of Sc, Y, Yb, Hf, Ce on Mechanical and Thermal Properties of La2Zr2O7: First-Principles Calculations

2015 ◽  
Vol 1120-1121 ◽  
pp. 85-93 ◽  
Author(s):  
Lei Jin ◽  
Pei Zhong Li ◽  
Chun Zhu Jiang ◽  
Guo Dong Zhou ◽  
Hai Bin Zhou ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Sound Velocity ◽  
Young’S Modulus ◽  
Debye Temperature ◽  
Elastic Constants ◽  
First Principles ◽  
Young's Modulus ◽  
Elastic Stiffness ◽  
Mechanical And Thermal Properties

In order to achieve better understanding of the effect of dopant (Sc, Y, Yb, Hf and Ce) on elastic stiffness and thermal properties of La2Zr2O7. The related calculations were performed using the first principles methods. The predicted elastic constants indicate that La2Zr2O7 and oxidations-La2Zr2O7 (oxidations refer to Sc2O3, Y2O3, Yb2O3, HfO2 and CeO2) are mechanically stable structures. And then the numerical estimates of bulk modulus, shear modulus, Young’s modulus were performed using the calculated elastic constants. After these mechanical properties are obtained, sound velocity, Debye temperature and theoretical minimum thermal conductivity of La2Zr2O7 and oxidations-La2Zr2O7 are calculated and analyzed in detail. The available experimental results and our calculations are basically satisfactory. The calculated results indicate that Young’s modulus, mean sound velocity, Debye temperature and minimum thermal conductivity of La2Zr2O7 can be decreased by dopants. CeO2 has extraordinary ability to decrease thermal conductivity in these dopant oxidations.

Ab Initio study of the crystal structure and the elastic properties of the Mo0.85Nb0.15B3 compound under pressure.

MRS Advances ◽  
2019 ◽  
Vol 4 (63) ◽  
pp. 3453-3461
Author(s):  
J. León-Flores ◽  
M. Romero ◽  
J. Rosas-Huerta ◽  
R. Escamilla
Keyword(s):  
Debye Temperature ◽  
Elastic Properties ◽  
First Principles ◽  
Poisson Ratio ◽  
Young Modulus ◽  
First Principles Calculations ◽  
Ab Initio Study ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Cauchy Pressure

ABSTRACTThe elastic constants, elastic modulus, anisotropy, Debye temperature, and sound velocity properties of Mo0.85Nb0.15B3 were investigated by first-principles calculations under pressure based on the generalized gradient approximation (GGA) proposed by Perdew–Burke-Ernzerhof (PBE). Employing the stress-strain method and the Voigt-Reuss-Hill approximations, were calculated the elastic properties of single and polycrystalline crystals; Bulk modulus (B), Young modulus (E), Poisson ratio (ν), Pugh ratio (G/B), Debye temperature and the Cauchy pressure terms. The calculated ν, Cauchy pressure, and Pugh ratio G/B values indicate that Mo0.85Nb0.15B3 shows a transition from brittle to ductile under pressure. Finally, the Density of States decreases as pressure increases.

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