First-Principles Simulations of Interstitial Atoms in Ionic Solids

1995 ◽  
Vol 408 ◽  
Author(s):  
E. A. Kotomin ◽  
A. Svane ◽  
T. Brudevoll ◽  
W. Schulz ◽  
N. E. Christensen
Keyword(s):  
Experimental Data ◽  
First Principles ◽  
Recent Experimental Data ◽  
Full Potential ◽  
Ionic Solids ◽  
Interstitial Atoms ◽  
Lmto Method ◽  
Radiation Induced ◽  
Anion Site ◽  
Molecular Mode

The atomic and electronic structure of the radiation-induced interstitial atoms in MgO and KCl crystals representing two broad classes of ionic solids are calculated and compared. The first-principles full potential LMTO method is applied to a 16-atom supercell. For both crystals the energetically most favourable configuration is a dumbbell centered at a regular anion site. Its (110) and (111) orientations are very close in energy which permits the dumbbell to rotate easily on a lattice site. The mechanism and the relevant activation energy for thermally activated diffusion hops from the dumbbell equilibrium position to the cube face and cube center are discussed in the light of the available experimental data for MgO. In order to interpret recent experimental data on Raman spectroscopy, the local vibrational frequences are calculated for the dumbbell in KCl (the so-called H center). A strong coupling is found between its stretching molecular mode and the breathing mode of the nearest cations whose frequency is predicted.

scholarly journals A first-principles investigation of band inversion in topologically nontrivial Na2AgX (X= As, Sb and Bi) full Heusler compounds

2021 ◽  
Vol 24 (2) ◽  
pp. 23602
Author(s):  
A. Boughena ◽  
S. Benalia ◽  
O. Cheref ◽  
N. Bettahar ◽  
D. Rached
Keyword(s):  
First Principles ◽  
Surface States ◽  
Metallic Surface ◽  
Full Potential ◽  
Topological Order ◽  
Heusler Compounds ◽  
Spin Orbital ◽  
Lmto Method ◽  
Potential Applications ◽  
Full Heusler

Topological nontrivial nature are the latest phases to be discovered in condensed matter physics with insulating bulk band gaps and topologically protected metallic surface states; they are one of the current hot topics because of their unique properties and potential applications. In this paper, we have highlighted a first-principles study of the structural stability and electronic behavior of the Na2AgX (X = As, Sb and Bi) full Heusler compounds, using the Full-Potential Linear Muffin-Tin Orbital (FP-LMTO) method. We have originated that the Hg2CuTi structure is appropriate in all studied materials. The negative values of the calculated formation energies mean that these compounds are energetically stable. The band structure is studied for the two cases relating the existence and the absence of spin-orbital couplings, where all materials are shown to be topologically non-trivial compounds. Spin orbital couplings were noticed to have no significant effect on the electronic properties such as the topological order.

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.

Structural and Electronic Properties of a Thin Metal-Silicide Film on Silicon Surface: A First-Principles Study

2003 ◽  
Vol 10 (02n03) ◽  
pp. 183-188 ◽  
Author(s):  
Byung Sub Kang ◽  
Hee Jae Kang ◽  
Suhk Kun Oh
Keyword(s):  
Electronic Properties ◽  
Structural Stability ◽  
First Principles ◽  
Structural Model ◽  
Surface Model ◽  
Full Potential ◽  
Surface And Interface ◽  
Structural And Electronic Properties ◽  
Lmto Method ◽  
Theoretical Results

The structural stability of metal (M) silicide (M = Co, Ni) phases and magnetic properties for the deposited one and two monolayers (ML) of M on the Si(001) surface was studied by the use of the ab initio full-potential linear muffin-tin orbital (FP-LMTO) method. The diffusion of M atoms on Si into the tetrahedral (fourfold M) sites was found to be energetically favorable. The deposited M atoms easily migrate into the bulk because the diffusion or interchange is energetically more favorable than the formation of cluster in a surface layer. The energetics for the structural stability of the "fourfold Si surface" model was compared with that of the sixfold structural model. Our results for the electronic properties of the MSi2/Si(001) surface and interface were compared with experimental and other theoretical results.

Electronic Structure of Planar Faults and Point Defects in High Temperature Intermetallics

1991 ◽  
Vol 253 ◽  
Author(s):  
J.M. Maclaren ◽  
C. Woodward
Keyword(s):  
Experimental Data ◽  
Electronic Structure ◽  
High Temperature ◽  
Point Defects ◽  
First Principles ◽  
Electronic Structure Calculations ◽  
Recent Experimental Data ◽  
Structure Calculations

ABSTRACTFirst principles electronic structure calculations, using the layer Korringa-Kohn-Rostoker method, are reported for isolated planar faults in TiAl. The calculated fault energies are discussed in the context of suggested superdislocation separation reactions. The influence of dilute impurities on fault energies are treated using the coherent potentialapproximation. Using this approach, the variation of fault energies in TiAl resulting from stoichiometry changes and from the addition of Mn axe calculated, and compared to recent experimental data.

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.

Calibration of Recoil-In-Vacuum attenuations from first principles: comparison with recent experimental data on Fe isotopes

2014 ◽  
Vol 230 (1-3) ◽  
pp. 169-174 ◽  
Author(s):  
Nicholas James Stone ◽  
Jirina Rikovska Stone ◽  
Andrew E. Stuchbery ◽  
Per Jonsson
Keyword(s):  
Experimental Data ◽  
First Principles ◽  
Recent Experimental Data ◽  
Fe Isotopes

Fusion and Breakup Reactions of 17S + 208Pb and 15C + 232ThHalo Nuclei Systems

2015 ◽  
Vol 11 (2) ◽  
pp. 2972-2978
Author(s):  
Fouad A. Majeed ◽  
Yousif A. Abdul-Hussien
Keyword(s):  
Experimental Data ◽  
Cross Section ◽  
Fusion Reaction ◽  
Fusion Cross Section ◽  
Reaction Cross ◽  
Recent Experimental Data ◽  
Barrier Distribution ◽  
Coupled Channel ◽  
Total Fusion ◽  
Full Quantum

In this study the calculations of the total fusion reaction cross section have been performed for fusion reaction systems 17F + 208Pb and 15C + 232Th which involving halo nuclei by using a semiclassical approach.The semiclassical treatment is comprising the WKB approximation to describe the relative motion between target and projectile nuclei, and Continuum Discretized Coupled Channel (CDCC) method to describe the intrinsic motion for both target and projectile nuclei. For the same of comparsion a full quantum mechanical clacualtions have been preforemd using the (CCFULL) code. Our theorticalrestuls are compared with the full quantum mechaincialcalcuations and with the recent experimental data for the total fusion reaction  checking the stability of the distancesThe coupled channel calculations of the total fusion cross section σfus, and the fusion barrier distribution Dfus. The comparsion with experiment proves that the semiclassiacl approach adopted in the present work reproduce the experimental data better that the full quantal mechanical calcautions. 

Effect of Different Input Loading Form on Structure-Born Sound Radiation

2012 ◽  
Vol 518-523 ◽  
pp. 3768-3771
Author(s):  
Zhi Yong Xie ◽  
Qi Dou Zhou ◽  
Gang Ji
Keyword(s):  
Experimental Data ◽  
Forced Vibration ◽  
Sound Radiation ◽  
Added Mass ◽  
Elastic Vibration ◽  
Simulation And Experiment ◽  
Radiation Induced ◽  
Vibration And Sound Radiation ◽  
Loading Form ◽  
Good Agreement

The exciting force’s accurate measurement of is crucial to the structure-born sound radiation. Forced vibration and sound radiation of the ribbed cylinder is examined in the anechoic room. An approach called added mass and damping method is proposed to calculate the elastic vibration and acoustic field of the cylinder. Results obtained from simulation are show to be in good agreement with the experimental data. Sound radiation induced by different input loading form is examined via simulation and experiment. And the equipollence of force and pressure acting on the base is validated.

Effect of Boron and Hydrogen on the Electronic Structure of Ni3Al

1993 ◽  
Vol 319 ◽  
Author(s):  
N. Kioussis ◽  
H. Watanabe ◽  
R.G. Hemker ◽  
W. Gourdin ◽  
A. Gonis ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Charge Density ◽  
First Principles ◽  
Electronic Structure Calculations ◽  
Interstitial Site ◽  
Octahedral Interstitial Site ◽  
Interstitial Region ◽  
Ordered Intermetallic ◽  
Lmto Method ◽  
Structure Calculations

AbstractUsing first-principles electronic structure calculations based on the Linear-Muffin-Tin Orbital (LMTO) method, we have investigated the effects of interstitial boron and hydrogen on the electronic structure of the L12 ordered intermetallic Ni3A1. When it occupies an octahedral interstitial site entirely coordinated by six Ni atoms, we find that boron enhances the charge distribution found in the strongly-bound “pure” Ni3AI crystal: Charge is depleted at Ni and Al sites and enhanced in interstitial region. Substitution of Al atoms for two of the Ni atoms coordinating the boron, however, reduces the interstitial charge density between certain atomic planes. In contrast to boron, hydrogen appears to deplete the interstitial charge, even when fully coordinated by Ni atoms. We suggest that these results are broadly consistent with the notion of boron as a cohesion enhancer and hydrogen as an embrittler.

FIRST-PRINCIPLES HIGH-PRESSURE ELASTIC AND THERMODYNAMIC PROPERTIES OF TANTALUM

2011 ◽  
Vol 25 (10) ◽  
pp. 1393-1407 ◽  
Author(s):  
JING-HE WU ◽  
XIAN-LIN ZHAO ◽  
YOU-LIN SONG ◽  
GUO-DONG WU
Keyword(s):  
Thermodynamic Properties ◽  
Elastic Constants ◽  
First Principles ◽  
Equations Of State ◽  
Debye Model ◽  
Thermal Expansivity ◽  
Orbital Method ◽  
Full Potential ◽  
Body Centered Cubic ◽  
Theoretical Results

The all-electron full-potential linearized muffin-tin orbital method, by means of quasi-harmonic Debye model, is applied to investigate the elastic constant and thermodynamic properties of body-centered-cubic tantalum (bcc Ta). The calculated elastic constants of bcc Ta at 0 K is consistent with the previous experimental and theoretical results. Our calculations give the correct trends for the pressure dependence of elastic constants. By using the convenient quasi-harmonic Debye model, we refined the thermal equations of state. The thermal expansivity and some other thermal properties agree well with the previous experimental and theoretical results.

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