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 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 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 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 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.

First Principles Calculation on Adsorption of S on Fe(100) with Different Pressure

2012 ◽  
Vol 217-219 ◽  
pp. 1811-1814
Author(s):  
Xue Tao Hu ◽  
Qiang Luo ◽  
Zeng Ling Ran
Keyword(s):  
Hydrostatic Pressure ◽  
Adsorption Energy ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculation ◽  
Hollow Site ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
Adsorption Energies

Using periodic density functional theory within the generalized-gradient approximation to electron exchange and correlation, we have studied S adsorption four-fold hollow site on Fe(100) in different hydrostatic pressure. We find that the adsorption height decreases with hydrostatic pressure increasing is non-monotonic. The adsorption energy decreases with an increase with pressure is monotonic and we have obtained density of states is almost unchanged, the adsorption energy change is mainly caused by lattice deformation in the hydrostatic pressure, and the adsorption energies increase linearly with pressure.

Hydrogen Atom Adsorption on α-Al2O3(0001) Surface from First Principles

2011 ◽  
Vol 399-401 ◽  
pp. 2261-2265 ◽  
Author(s):  
Jian Gong Hu ◽  
Yi Sheng Zhang ◽  
Li Chao Jia ◽  
Bin Zhu ◽  
Hong Guang Yang ◽  
...  
Keyword(s):  
Adsorption Energy ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculation ◽  
Large Decrease ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
The Density Functional Theory ◽  
Low Coverage

First-principles calculation based on the density functional theory in the generalized gradient approximation was adopted to systematically investigate the α-Al2O3(0001) surface structure and the adsorption of H atom on the α-Al2O3(0001) surface. The calculations show that the O atop site is the energetically most favorable adsorption site at low coverage: at the H coverage of 1/6 ML (monolayer), the adsorption energy reaches up to7.61eV; in the regime of higher H coverages, the H atoms prefer to form atom cluster on the α-Al2O3(0001) surface, and the adsorption energy on the α-Al2O3(0001) with a pre-adsorbed H atom gets smaller, which illustrates that α-Al2O3that can prevent the penetration of hydrogen. With the increase of H coverage, the dipole moment reduces, which leads to a large decrease in the work function.

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 study of the structural, electronic and optical properties of crystalline o-phenanthroline

2016 ◽  
Vol 30 (14) ◽  
pp. 1650077 ◽  
Author(s):  
Hajar Nejatipour ◽  
Mehrdad Dadsetani
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Binding Energies ◽  
Many Body ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Independent Particle ◽  
Excitonic Effects ◽  
Comprehensive Study

In a comprehensive study, structural properties, electronic structure and optical response of crystalline o-phenanthroline were investigated. Our results show that in generalized gradient approximation (GGA) approximation, o-phenanthroline is a direct bandgap semiconductor of 2.60 eV. In the framework of many-body approach, by solving the Bethe–Salpeter equation (BSE), dielectric properties of crystalline o-phenanthroline were studied and compared with phenanthrene. Highly anisotropic components of the imaginary part of the macroscopic dielectric function in o-phenanthroline show four main excitonic features in the bandgap region. In comparison to phenanthrene, these excitons occur at lower energies. Due to smaller bond lengths originated from the polarity nature of bonds in presence of nitrogen atoms, denser packing, and therefore, a weaker screening effect, exciton binding energies in o-phenanthroline were found to be larger than those in phenanthrene. Our results showed that in comparison to the independent-particle picture, excitonic effects highly redistribute the oscillator strength.

First-Principles Investigation on Elastic Constants of TiN under High Pressure

2013 ◽  
Vol 802 ◽  
pp. 109-113
Author(s):  
Kittiya Prasert ◽  
Pitiporn Thanomngam ◽  
Kanoknan Sarasamak
Keyword(s):  
Elastic Constants ◽  
First Principles ◽  
Local Density ◽  
Ambient Pressure ◽  
Lattice Parameter ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Shear Distortion ◽  
Calculated Lattice Parameter

Elastic constants of NaCl-type TiN under pressure were investigated by first-principles calculations within both local density approximation (LDA) and Perdew-Burke-Ernzerhof generalized-gradient approximation (PBE-GGA). At ambient pressure, the calculated lattice parameter, bulk modulus, and elastic constants of NaCl-type TiN are in well agreement with other available values. Under pressure, all elastic constants,C11,C12, andC44, are found to increase with pressure.C11, which is related to the longitudinal distortion, increases rapidly with pressure whileC12andC44which are related to the transverse and shear distortion, respectively, are much less sensitive to pressure.

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