First-Principles Computation of Transition-Metal Diffusion Mobility

2007 ◽  
Vol 266 ◽  
pp. 73-82 ◽  
Author(s):  
Kwai S. Chan ◽  
Yi Ming Pan ◽  
Yi Der Lee
Keyword(s):  
First Principles ◽  
Diffusion Processes ◽  
Local Density ◽  
Computational Procedure ◽  
Diffusion Mobility ◽  
Vacancy Formation ◽  
Full Potential ◽  
Self Diffusion ◽  
Metal Diffusion ◽  
Host Metal

First–principle computational methods have been utilized to compute the diffusion mobility of Mo, Cr, Fe, and W. A local density-based full-potential linearized augmented plane wave (FLAPW) code, named WIEN2K, was utilized to compute the electronic structure and total energy of an n-atom supercell with atom positions designed to simulate the desired diffusion processes. The computational procedure involves the calculations of the energy for vacancy formation and the energy barrier for solute migration in the host metal. First-principles computational results of the energy of vacancy formation, solute migration energy, activation energy for self-diffusion, as well as diffusion of Mo, Cr, Fe, and W solutes in Ni and vice versa are presented and compared against experimental data from the literature.

Electronic and Optical Properties of Si/SiO2 Superlattices from First Principles: Role of Interfaces.

2001 ◽  
Vol 677 ◽  
Author(s):  
Pierre Carrier ◽  
Gilles Abramovici ◽  
Laurent J. Lewis ◽  
M. W. C. Dharma-wardana
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Energy Gap ◽  
Local Density ◽  
Interband Transition ◽  
Theoretical Research ◽  
Slab Thickness ◽  
Full Potential ◽  
Wave Method

ABSTRACTThe observation of intense luminescence in Si/SiO2 superlattices (SLs) has lead to new theoretical research on silicon-based materials. We have performed first-principles calculations using three Si/SiO2 SL models in order to examine the role of interfaces on the electronic structure and optical properties. The first two models are derived directly from crystalline structures and have simple interfaces. These models have been studied using the full-potential, linearized-augmented-plane-wave method, in the local-density-approximation (LDA). The optical absorption within the interband transition theory (excluding excitonic effects) have been deduced. The Si(001)-SiO2 interface structure is shown to affect the optical behaviour. Following these observations, we have considered a more realistic, fully-relaxed model. The projector-augmented-wave method under the LDA is used to perform the structural relaxation as well as band structure and optical calculations. The role of confinement on the energy gap is studied by inserting additional silicon slabs into the supercell. Direct energy gaps are observed and the energy gap is found to decrease with increasing silicon slab thickness, as observed experimentally. The role of the interface has been considered in more details by studying the contribution to the energy gap of Si atoms having different oxidation patterns; partially oxidized Si atoms at the interface, as well as Si atoms inside the Si layer, are shown to contribute to the transitions at the energy gap.

First-principles calculations to investigate structural, electronic and optical properties of (ZnSe)n/(ZnTe)n superlattices

2020 ◽  
Author(s):  
Messaoud Caid
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Correlation Energy ◽  
Local Density ◽  
Full Potential ◽  
First Principles Calculations ◽  
Electronic And Optical Properties ◽  
Lmto Method ◽  
Binary Compounds

An investigation into the structural, electronic and optical properties of superlattices(SLs) (ZnSe)n/(ZnTe)n was conducted using first principles calculations based on density functional theory (DFT). The total energies were calculated within the full-potential linear muffin-tin orbital (FP-LMTO) method augmented by a plane-wave basis (PLW), implemented in LmtART 7.0 code. The effects of the approximations to the exchange-correlation energy were treated by the local density approximation (LDA). The ground state properties of (ZnSe)n/(ZnTe)n binary compounds are determined and compared with the available data. It is found that the superlattice (n-n: 1-1, 2-2 and 3-3) band gaps vary depending on the layers used. The optical constants, including the dielectric function ε(w), the refractive index n(w) and the reflectivity R(w), are calculated for radiation energies up to 35eV.

A simple model for calculating the compressibility of the transition-metal carbides and nitrides alloys ZrxNb1−xC and ZrxNb1−xN

Open Physics ◽  
2011 ◽  
Vol 9 (5) ◽  
Author(s):  
Vassiliki Katsika-Tsigourakou
Keyword(s):  
First Principles ◽  
Local Density ◽  
Plane Waves ◽  
Ternary Alloys ◽  
Full Potential ◽  
First Principles Calculations ◽  
Metal Carbides ◽  
Rocksalt Structure ◽  
Mechanical And Physical Properties ◽  
End Members

AbstractThe 4d-transition-metals carbides (ZrC, NbC) and nitrides (ZrN, NbN) in the rocksalt structure, as well as their ternary alloys, have been recently studied by means of a first-principles full potential linearized augmented plane waves method within the local density approximation. These materials are important because of their interesting mechanical and physical properties, which make them suitable for many technological applications. Here, by using a simple theoretical model, we estimate the bulk moduli of their ternary alloys ZrxNb1−xC and ZrxNb1−xN in terms of the bulk moduli of the end members alone. The results are comparable to those deduced from the first-principles calculations.

First principles studies of self-diffusion processes on metallic lithium surfaces

2019 ◽  
Vol 150 (4) ◽  
pp. 041723 ◽  
Author(s):  
Daniel Gaissmaier ◽  
Donato Fantauzzi ◽  
Timo Jacob
Keyword(s):  
First Principles ◽  
Diffusion Processes ◽  
Self Diffusion ◽  
Metallic Lithium

Elastic Constants and Related Properties of the Group III-Nitrides

1995 ◽  
Vol 395 ◽  
Author(s):  
Kwiseon Kim ◽  
Walter R. L. Lambrecht ◽  
B. Segall
Keyword(s):  
Elastic Constants ◽  
First Principles ◽  
Bond Angle ◽  
Local Density ◽  
Group Iii Nitrides ◽  
Internal Displacement ◽  
Orbital Method ◽  
Model Parameters ◽  
Full Potential ◽  
Group Iii

ABSTRACTThe elastic constants of the Group-III nitrides, c-BN, AlN and GaN were calculated from first-principles using the full-potential linear muffin-tin orbital method and local density approximation. The relation between the elatic constants in zincblende and wurtzite is studied by means of a tensor coordinate transformation approach. The latter combined with a correction for the internal displacement of the rotated tetrahedra is found to provide good results for the Ch11Ch12 and Ch44 but not for Ch13 and Ch33. These two require explicit calculations involving distortions along the c-axis. The calculations also provide information on the transverse optical phonons. By deriving Keating model parameters we show that BN is much stiffer against bond-angle distortions than the other nitrides.

Studies of Large Lithium Clusters and their Vacancies with Highly Optimized Localized Orbitals

1988 ◽  
Vol 141 ◽  
Author(s):  
Mark R. Pederson ◽  
Joseph G. Harrison ◽  
Barry M. Klein
Keyword(s):  
First Principles ◽  
Formation Energy ◽  
Local Density ◽  
Lattice Relaxation ◽  
Vacancy Formation ◽  
Experimental Result ◽  
Cohesive Energies ◽  
Formation Energies ◽  
Lithium Clusters ◽  
Good Agreement

AbstractA first-principles local-density based algorithm which employs optimized Gaussian-type orbitals is used to carry out calculations on a large variety of lithium clusters consisting of one to twenty-seven atoms. Bulk moduli, bond lengths and cohesive energies for the isolated clusters are presented and the results are extrapolated so as to predict the bulk (BCC) cohesive energy as well. Vacancy formation energies and vacancy induced lattice relaxation are also presented for three BCC fragments and compared to the bulk experimental results. For our largest cluster, we obtain a vacancy formation energy of 0.36 eV which is in good agreement with the experimental result of 0.34 eV.

FIRST PRINCIPLES STUDY OF THE STRUCTURAL, ELASTIC AND ELECTRONIC PROPERTIES OF Ti2InC and Ti2InN

2011 ◽  
Vol 25 (10) ◽  
pp. 747-761 ◽  
Author(s):  
N. BENAYAD ◽  
D. RACHED ◽  
R. KHENATA ◽  
F. LITIMEIN ◽  
ALI H. RESHAK ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Electronic Properties ◽  
First Principles ◽  
Local Density ◽  
Full Potential ◽  
Pressure Derivative ◽  
Lattice Constants ◽  
Internal Parameters ◽  
Correlation Potential ◽  
Lmto Method

The structural, elastic and electronic properties of Ti 2 InC and Ti 2 InN compounds have been calculated using the full-potential linear muffin-tin orbital (FP-LMTO) method. The exchange and correlation potential is treated by the local density approximation (LDA). The calculated ground state properties, including, lattice constants, internal parameters, bulk modulus and the pressure derivative of the bulk modulus are in reasonable agreement with the available data. The effect of pressure, up to 40 GPa, on the lattice constants and the internal parameters is also investigated. Using the total energy-strain technique, we have determined the elastic constants Cij, which have not been measured yet. The band structure and the density of states (DOS) show that both materials have a metallic character and Ti 2 InN is more conducting than Ti 2 InC . The analysis of the site and momentum projected densities shows that the bonding is achieved through a hybridization of Ti -atom d states with C ( N )-atom p states. Otherwise, it has been shown that Ti – C and Ti – N bonds are stronger than Ti – In bonds.

First principles calculation of the elastic constants of intermetallic compounds: metastable Al3Li

1991 ◽  
Vol 6 (2) ◽  
pp. 324-329 ◽  
Author(s):  
X-Q. Guo ◽  
R. Podloucky ◽  
A.J. Freeman
Keyword(s):  
Young’S Modulus ◽  
Elastic Constants ◽  
First Principles ◽  
Local Density ◽  
Young's Modulus ◽  
Poisson Ratio ◽  
First Principles Calculation ◽  
Full Potential ◽  
A Value ◽  
Experimental Values

We report first principles local density calculations for the metastable Al3Li intermetallic compound with cubic L12 crystal structure using the full-potential linearized augmented plane wave method. From the second derivative of the total energy as a function of volume, and generated tetragonal and trigonal lattice distortions, the elastic constants C11, C12, and C44 were derived yielding C11 = 158 GPa, C12 = 29.4 GPa, and C44 = 57.7 GPa. Because of the very high Young's modulus (E = 141 GPa) compared, for example, to pure Al (E = 66 GPa), it is suggested that Al3Li plays an important role in strengthening the Al–Li alloys. The calculated Young's modulus appears in good agreement with experimental estimates when the experimental values are extrapolated to 0 K. Although the Young's modulus of Al3Li is increased in comparison to Al, the calculated bulk modulus is decreased to a value of 72 GPa as compared to pure Al (82 GPa), in agreement with experiment. As a result, the Poisson ratio is reduced to ŝ = 0.173 as compared to the value 1/3 for an isotropic medium. Because of this and the high Young's modulus, the calculated Debye temperature ΘD at 0 K amounts to 672 K, which is substantially larger than ΘD for Al, which is about 400 K.

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