scholarly journals Structural Optimization, Electronic Band Structure, Mechanical and Thermodynamics Properties of Fe3Al

2021 ◽  
pp. 1-11
Author(s):  
I. S. Okunzuwa ◽  
E. Aigbekaen Eddy
Keyword(s):  
Density Functional ◽  
Electronic Band Structure ◽  
Plane Waves ◽  
State Density ◽  
Structural Parameter ◽  
Mechanical And Thermal Properties ◽  
Energy Bands ◽  
Electronic Band ◽  
Salt Structure ◽  
Quantum Espresso

We calculated the structural, electronic, mechanical and thermal properties of Fe3Al semiconducting using Quantum ESPRESSO, an open source first principles code based on density-functional theory, plane waves, and pseudopotentials. Structural parameter results (equilibrium lattice parameters, bulk modulus and its derivative pressure) have been reported. The underestimated band gap is obtained along with higher state density and energy bands around the fermi level. Mechanical properties of the rock-salt structure of Fe3Al, such as, shear modulus (G), Young’s modulus (E), and Poisson’s ratio () were investigated. The thermodynamic parameters are also present. The results are in good agreement with the available experimental and other theoretical results.

Ab-initio prediction of structural, electronic and magnetic properties of Hexafluoromanganete(IV) complexes

2018 ◽  
Vol 32 (24) ◽  
pp. 1850270 ◽  
Author(s):  
M. Faizan ◽  
S. H. Khan ◽  
A. Khan ◽  
A. Laref ◽  
G. Murtaza
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Correlation Energy ◽  
Electronic Band Structure ◽  
Wide Bandgap ◽  
Energy Bands ◽  
Electronic Band ◽  
Metallic Behavior ◽  
Half Metallic ◽  
Exchange Correlation

In this work, detailed electronic structure calculations of alkali metal fluorides A2MnF6 (A = K, Rb, Cs) have been performed using ab-initio calculating techniques based on density functional theory (DFT). We applied different exchange correlation functionals, namely Wu–Cohen generalized gradient approximation (WC-GGA), modified Becke Johnson potential (mBJ) and GGA plus Hubbard U method in order to treat the exchange correlation energy. The calculated lattice constants are found in excellent agreement with earlier experimental results. The electronic band structure and density of states show that Cs2MnF6 is half metallic, exhibiting semiconductivity in spin up direction and metallic behavior in spin down direction. The compounds, K2MnF6 and Rb2MnF6, are predicted as wide bandgap materials. The DFT + U method gives quite accurate results of the electronic bandgap as compared with other approximations. The states Mn-3d and F-2p contribute largely to the conduction and valence energy bands. Additionally, magnetic calculations reveal strong ferromagnetic nature of these compounds. The half-metallic nature along with ferromagnetism make Cs2MnF6 a promising candidate for future applications in spintronics. Furthermore, the wide bandgap observed in K2MnF6 and Rb2MnF6 indicate their utility for light-emitting diodes (LEDs) transparent lenses and optical coatings.

Effect of Sr - Transition Metal Substitution on Electronic and Mechanical Properties of Mg2Si: A DFT Study

2021 ◽  
Vol 14 (3) ◽  
pp. 255-265
Keyword(s):  
Mechanical Properties ◽  
Elastic Constants ◽  
Density Functional ◽  
Plane Waves ◽  
Three Dimensional ◽  
Anisotropy Parameter ◽  
Electronic Band ◽  
The Density Functional Theory ◽  
Direct Band ◽  
Quantum Espresso

Abstract: Recently, magnesium alloys have attracted scientific interest due to their technological importance in thermoelectric, piezoelectric, photo-voltaic and infrared photonics applications. The electronic and elastic properties of MgXSi (X = Mg, Sr) compounds were investigated in this work, using the density functional theory (DFT) with pseudo-potential plane-waves (PPW) approach as implemented in Quantum Espresso code. The results of the elastic constants of Mg2Si are in agreement with the previous theoretical results and favourably compared with experimental data. The electronic band structures of these semiconductors were calculated to give narrow indirect and direct band gaps of Mg2Si and MgSrSi, respectively. Our results show that the two compounds are mechanically stable. The Pugh’s ratio, B/G, indicated that Mg2Si and MgSrSi are brittle and ductile in nature. The estimated anisotropy parameter, A, shows that Mg2Si has a higher degree of elastic isotropy in comparison to MgSrSi. Three-dimensional (3D) projection of Young’s modulus and area modulus of the compounds was presented. Keywords: Electronic structure, Elastic constants, Mechanical properties, Mg2Si, MgSrSi. PACS: 31.15.A-, 62.20.F-, 71.55.-i, 71.20.Be.

Surface Structure and Electronic Property of Sulfur Passivation of InAs(001) Surface: A First-Principles Study

2011 ◽  
Vol 689 ◽  
pp. 220-225
Author(s):  
Deng Feng Li ◽  
Zhi Cheng Guo ◽  
Bo Deng ◽  
Hui Ning Dong ◽  
Fei Gao
Keyword(s):  
Surface State ◽  
Density Functional ◽  
Electronic Band Structure ◽  
State Density ◽  
Electronic Band ◽  
Surface State Density ◽  
Structural And Electronic Properties ◽  
Sulfur Passivation ◽  
Adsorption Geometry ◽  
Sulfur Adsorption

Using density functional theory, we have studied surface structural and electronic properties of sulfur adsorption on As-terminated and In-terminated InAs(001) surfaces with the coverage (Θ) of 0.5ML and 1ML. Based on adsorption energy calculations, we found that atΘ=0.5ML, S adatoms preferred to replace the As atoms at As-terminated InAs(001)(2×1) surface. For 1ML S adsorption on InAs(001)(2×1) surface, the most stable adsorption geometry is S-S dimers covered on the In-terminated surface. This result is different from that for 1ML S adsorption on GaP(001) and InP(001) surfaces, and it is consistent with the experimental results. The electronic band structure analysis showed that the surface state density around the Fermi level was considerably diminished for 0.5ML S adsorption on As-terminated InAs(001)(2×1) surface at substitution site. The surface state density of S-S dimer adsorption on In-terminated (2×1) surface was strengthened due to one excess valence electron on the surface.

ELECTRONIC STRUCTURE, MAGNETIC ORDERING AND PHASE STABILITY OF LiFeX (X = P, As and Sb) UNDER PRESSURE

2013 ◽  
Vol 27 (32) ◽  
pp. 1350236 ◽  
Author(s):  
RAJENDRAN MAHESH ◽  
RAMASWAMY MURUGAN ◽  
BALAN PALANIVEL
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Magnetic Ordering ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Electronic Band ◽  
Electron Phonon Coupling ◽  
Total Energies ◽  
Quantum Espresso

Electronic band structure calculations were performed on the nonmagnetc (NM) and antiferromagnetic (AFM) phases of LiFe X (X = P , As and Sb ) compounds using ab initio method. The crystal structure of these compounds is well tetragonal P4/nmm structure (space group = 129). Self-consistent calculations were performed by planewave pseudo-potential, density functional based method using PWSCF-Quantum Espresso code. To study the electronic structure and magnetic ordering, the total energies of these compounds have been computed as a function of reduced volumes and fitted with Brich Murnaghan equation. The estimated lattice parameters are in good agreement with available experimental data. The calculated Fe magnetic moment for LiFeSb is larger than LiFeAs and LiFeP . The obtained electron–phonon coupling constant (λ) for the NM phase are very weak when compared to that of AFM phase of LiFe X compounds. Present calculations reveal that the electron–phonon coupling constant λ decreases as a function of pressure.

scholarly journals Ab Initio Study of Structure, Electronic and Magnetic Properties of YFe5 Phase Compound in the DFT Formalism

2016 ◽  
Vol 61 (1) ◽  
pp. 369-374 ◽  
Author(s):  
K. Gruszka ◽  
M. Nabiałek ◽  
T. Noga
Keyword(s):  
Magnetic Properties ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Population Analysis ◽  
Ab Initio Study ◽  
Electronic Band ◽  
Functional Theory ◽  
Electronic And Magnetic Properties ◽  
Phase Compound ◽  
Quantum Espresso

Paper presents results of studies on structural, electronic and magnetic properties of YFe5 compound using density functional theory (DFT) approach. The GGA functional with ultrasoft pseudopotentials were used as implemented in Quantum Espresso software. The structure of YFe5 compound was examined in three different states namely nonmagnetic, antiferromagnetic and ferromagnetic. Also two antiferromagnetic configurations were considered. From the total energy viewpoint the most likely ferromagnetic configuration is favorable. In order to achieve mentioned aims we present projected density of states, electronic band structure and Löwdin population analysis studies results.

scholarly journals Optimizing Configurations for Determining the Electromagnetic Properties of CsFeF3, NaFeF3, and RbFeF3 Fluorides: GGA vs GGA+U and TB-mBj Approaches

2020 ◽  
Vol 62 (1) ◽  
pp. 71-94
Author(s):  
Filalli Sihem ◽  
Hamdad Noura
Keyword(s):  
Density Functional ◽  
Electronic Band Structure ◽  
Structural Parameters ◽  
Magnetic Moments ◽  
Plane Waves ◽  
Electromagnetic Properties ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Covalent Interaction

AbstractThe structural, electronic and magnetic properties of (Cubic Pm-3m, Hexagonal-4H, orthorhombic Pnma, and orthorhombic Pbnm) phases of AFeF3 Fluorides (A = Cs, Na, and Rb) are reported theoretically using full potential linearized augmented plane waves method within the density functional theory (DFT). Using different exchange–correlation approximations including the generalized gradient approximation (PBE-GGA, WC-GGA, and PBEsol-GGA), also (GGA) with Hubbard potential (GGA + U) and The modified Becke Johnson potential (mBJ), we carried to determine various physical properties. The Calculations revealing that the estimated structural parameters are reliable with the experimentally reported data. Magnetically all these intermetallics are Ferromagnetic (FM). The ground-state energy of different magnetic phases studied showed that the magnetic moments are evaluated per atom, and overestimated by (GGA+U). Transfer charge reveals a strong covalent interaction between Fe-Fe atoms. Their electronic band structure and density of states indicate insulator behavior.

Ab initio calculation on the Optical Properties of AA- Stacked two dimensional Graphene, Silicene, Germanene, and Stanene

2018 ◽  
Vol 1 (1) ◽  
pp. 46-50
Author(s):  
Rita John ◽  
Benita Merlin
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Complex Refractive Index ◽  
Single Layer ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Wide Range ◽  
Optical Region

In this study, we have analyzed the electronic band structure and optical properties of AA-stacked bilayer graphene and its 2D analogues and compared the results with single layers. The calculations have been done using Density Functional Theory with Generalized Gradient Approximation as exchange correlation potential as in CASTEP. The study on electronic band structure shows the splitting of valence and conduction bands. A band gap of 0.342eV in graphene and an infinitesimally small gap in other 2D materials are generated. Similar to a single layer, AA-stacked bilayer materials also exhibit excellent optical properties throughout the optical region from infrared to ultraviolet. Optical properties are studied along both parallel (||) and perpendicular ( ) polarization directions. The complex dielectric function (ε) and the complex refractive index (N) are calculated. The calculated values of ε and N enable us to analyze optical absorption, reflectivity, conductivity, and the electron loss function. Inferences from the study of optical properties are presented. In general the optical properties are found to be enhanced compared to its corresponding single layer. The further study brings out greater inferences towards their direct application in the optical industry through a wide range of the optical spectrum.

First principles calculation of structural, electronic and optical properties of (001) and (110) growth axis (InN)/(GaN)n superlattices

2021 ◽  
Vol 67 (1 Jan-Feb) ◽  
pp. 7
Author(s):  
B. Bachir Bouiadjra ◽  
N. Mehnane ◽  
N. Oukli
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Scale Up ◽  
Energy Scale ◽  
First Principles Calculation ◽  
Full Potential ◽  
Electronic Band ◽  
Electronic And Optical Properties ◽  
Growth Axis

Based on the full potential linear muffin-tin orbitals (FPLMTO) calculation within density functional theory, we systematically investigate the electronic and optical properties of (100) and (110)-oriented (InN)/(GaN)n zinc-blende superlattice with one InN monolayer and with different numbers of GaN monolayers. Specifically, the electronic band structure calculations and their related features, like the absorption coefficient and refractive index of these systems are computed over a wide photon energy scale up to 20 eV. The effect of periodicity layer numbers n on the band gaps and the optical activity of (InN)/(GaN)n SLs in the both  growth axis (001) and (110) are examined and compared. Because of prospective optical aspects of (InN)/(GaN)n such as light-emitting applications, this theoretical study can help the experimental measurements.

scholarly journals Research on Molecular Structure and Electronic Properties of Ln3+ (Ce3+, Tb3+, Pr3+)/Li+ and Eu2+ Co-Doped Sr2Si5N8 via DFT Calculation

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1849
Author(s):  
Ziqian Yin ◽  
Meijuan Li ◽  
Jianwen Zhang ◽  
Qiang Shen
Keyword(s):  
Molecular Structure ◽  
Energy Level ◽  
Density Functional ◽  
Formation Energy ◽  
Electronic Band Structure ◽  
Blue Shift ◽  
Lanthanide Ions ◽  
Partial Replacement ◽  
Electronic Band ◽  
Charge Imbalance

We use density functional theory (DFT) to study the molecular structure and electronic band structure of Sr2Si5N8:Eu2+ doped with trivalent lanthanides (Ln3+ = Ce3+, Tb3+, Pr3+). Li+ was used as a charge compensator for the charge imbalance caused by the partial replacement of Sr2+ by Ln3+. The doping of Ln lanthanide atom causes the structure of Sr2Si5N8 lattice to shrink due to the smaller atomic radius of Ln3+ and Li+ compared to Sr2+. The doped structure’s formation energy indicates that the formation energy of Li+, which is used to compensate for the charge imbalance, is the lowest when the Sr2 site is doped. Thus, a suitable Li+ doping site for double-doped lanthanide ions can be provided. In Sr2Si5N8:Eu2+, the doped Ce3+ can occupy partly the site of Sr12+ ([SrN8]), while Eu2+ accounts for Sr12+ and Sr22+ ([SrN10]). When the Pr3+ ion is selected as the dopant in Sr2Si5N8:Eu2+, Pr3+ and Eu2+ would replace Sr22+ simultaneously. In this theoretical model, the replacement of Sr2+ by Tb3+ cannot exist reasonably. For the electronic structure, the energy level of Sr2Si5N8:Eu2+/Li+ doped with Ce3+ and Pr3+ appears at the bottom of the conduction band or in the forbidden band, which reduces the energy bandgap of Sr2Si5N8. We use DFT+U to adjust the lanthanide ion 4f energy level. The adjusted 4f-CBM of CeSr1LiSr1-Sr2Si5N8 is from 2.42 to 2.85 eV. The energy range of 4f-CBM in PrSr1LiSr1-Sr2Si5N8 is 2.75–2.99 eV and its peak is 2.90 eV; the addition of Ce3+ in EuSr1CeSr1LiSr1 made the 4f energy level of Eu2+ blue shift. The addition of Pr3+ in EuSr2PrSr2LiSr1 makes part of the Eu2+ 4f energy level blue shift. Eu2+ 4f energy level in EuSr2CeSr1LiSr1 is not in the forbidden band, so Eu2+ is not used as the emission center.

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