Theoretical calculations of the NiAl-NiTi phase diagram based on first-principles linear-muffin-tin-orbital and full-potential linearly-augmented plane-wave cohesive-energy calculations

1992 ◽  
Vol 45 (14) ◽  
pp. 7677-7683 ◽  
Author(s):  
Benjamin P. Burton ◽  
Jean E. Osburn ◽  
Alain Pasturel
Keyword(s):  
Phase Diagram ◽  
Plane Wave ◽  
First Principles ◽  
Cohesive Energy ◽  
Theoretical Calculations ◽  
Full Potential ◽  
Augmented Plane Wave ◽  
Energy Calculations ◽  
Niti Phase ◽  
Linear Muffin Tin Orbital

Evolution of the electronic structure of metallic multilayers from two to threedimensionality. A Full Potential Linearized Augmented Plane Wave calculation.

2002 ◽  
Vol 727 ◽  
Author(s):  
A. M. Mazzone
Keyword(s):  
Plane Wave ◽  
Density Of States ◽  
Noble Metals ◽  
Full Potential ◽  
Metallic Multilayers ◽  
Augmented Plane Wave ◽  
Narrow Bandwidth ◽  
Epitaxial Multilayers ◽  
Linearized Augmented Plane Wave ◽  
Wave Calculation

AbstractFull Potential Linearized Augmented Plane Wave calculations have been performed for epitaxial multilayers formed by the noble metals Ag and Cu with a thickness n up to 10 layers. The multilayers have a fcc lattice and are pure or compositionally modulated with a structure of the type Agn Cun or (AgCu)n. For n in the range 2,3 the density of states, evaluated at paramagnetic level, exhibits a sharp reduction of the bandwidth which is consistent with the reduced coordination of these structures. For n ≤ 5 the density of states in the central layers converges to the bulk value while the outer layers retain the narrow bandwidth found at n=2. Due to the absence of charge intermixing and hybridization, these features are shared by multilayers of all composition.

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.

Augmented Plane Wave Study of Electric Field Gradients in Non-cubic Metals

1990 ◽  
Vol 45 (3-4) ◽  
pp. 368-374 ◽  
Author(s):  
R. Leiberich ◽  
P. C. Schmidt ◽  
N. Sahoo ◽  
T. P. Das
Keyword(s):  
Plane Wave ◽  
Electric Field ◽  
Full Potential ◽  
Augmented Plane Wave ◽  
Cubic Metals ◽  
Field Gradients ◽  
Valence Electrons ◽  
Electron Contribution ◽  
Ionic Contribution ◽  
Beryllium Metal

Abstract The electric field gradient (EFG) in body-centered tetragonal Indium metal and hexagonal closed packed Beryllium metal is calculated on the basis of a full potential scalar relativistic augmented plane wave procedure. The various contributions to the EFG in simple metals are discussed. The total EFG in In metal found theoretically is equal to qtheor = 2.67 x 1021 Vm-2 . This value agrees well with the experimental data. Using the quadrupole moment Q deduced from the hyperfine splitting of the muon X-ray spectra one gets g exp = 2.46 x 1021 Vm-2 . The valence electrons of Indium give a direct contribution of qel = 2.72 x 1021 Vm-2 , whereas the direct ionic contribution q ion is much smaller and has opposite sign: qion = -0.01 x 1021 Vm-2 . There is a small net shielding contribution of qsh = -0.03 x 1021 Vm-2 to the EFG composed of the ionic contribution gsh. ion = -0.39 x 1021 Vm- 2 and the valence electron contribution qsh,ve = 0.36 x 10 21 Vm-2 .

Influence of Pre-Deformation Temperature on Mechanics Performance of NiTiNb Shape Memory Alloy: First-Principles Calculation

2014 ◽  
Vol 1004-1005 ◽  
pp. 163-167
Author(s):  
Hong Chang Zhu ◽  
Fu Sheng Yanguan ◽  
Gui Fa Li ◽  
Ping Peng
Keyword(s):  
First Principles ◽  
Cohesive Energy ◽  
Deformation Temperature ◽  
Local Maximum ◽  
First Principles Calculation ◽  
Maximum Value ◽  
Niti Phase ◽  
Mechanics Performance ◽  
Valence Electrons ◽  
The Matrix

Based on first-principles calculation, the mechanism of optimal pre-deformation temperature (Ms+30) for NiTiNb alloy was characterized and analyzed by several parameters, such as crystal constant, cohesive energy and the elastic constants. Simulation results showed that the shear modulus c′ and c44 of matrix NiTi phase was softened at 208K. At the same time, its cohesive energy obtained its local maximum value, which was originated from the easy transition ability of valence electrons in d orbital. In other words, the matrix NiTi phase was instable only when the pre-deformed temperature was not only for Ms but also to 208K (Ms+30K).

Theoretical study of point defects in GaN and AlN; lattice relaxations and pressure effects

1997 ◽  
Vol 2 ◽  
Author(s):  
I. Gorczyca ◽  
A. Svane ◽  
N. E. Christensen
Keyword(s):  
Theoretical Calculations ◽  
Pressure Effects ◽  
Function Technique ◽  
Orbital Method ◽  
Full Potential ◽  
Cation Site ◽  
Carbon Impurity ◽  
Atomic Displacements ◽  
Cubic Gan ◽  
Linear Muffin Tin Orbital

Native defects and some common dopants (Mg, Zn, and C) in cubic GaN and AlN are examined by means of ab initio theoretical calculations using two methods: i) the Green's function technique based on the linear muffin-tin orbital method in the atomic-spheres approximation; ii) a supercell approach in connection with the full-potential linear muffin-tin-orbital method. We apply the first method to look mainly at the energetic positions of the defect and impurity states in different charge states and their dependence on hydrostatic pressure. The second method allows us to study lattice relaxations. Whereas small relaxations are found near vacancies and substitutional Mg and Zn, the calculations predict large atomic displacements around antisite defects and the substitutional carbon impurity on the cation site.

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