Effect of Temperature/Pressure on Lattice Dynamics of FeNi

2016 ◽  
Vol 1141 ◽  
pp. 84-90 ◽  
Author(s):  
N.Y. Pandya ◽  
A.D. Mevada ◽  
P.N. Gajjar
Keyword(s):  
Density Of States ◽  
Density Functional ◽  
Phonon Dispersion ◽  
Electronic Band Structure ◽  
Effect Of Temperature ◽  
Electronic Band ◽  
Functional Theory ◽  
Phonon Dispersion Curves ◽  
Consistent Method ◽  
Hard Ferromagnet

Tetratenite phase of L10 (CuAu) FeNi is identified as a hard ferromagnet in spite of that common FeNi alloys are classified as a soft magnet. Due to its strong magnetic anisotropy and large coercivity, tetrataenite phase of L10 FeNi is under investigation as a rare earth free advanced permanent magnet. Our computed equilibrium lattice constant and c/a ratio for tetratenite phase of L10 (CuAu) FeNi are in 10 % deviation with the other available results. The vibrational and electronic properties of L10 FeNi at finite temperatures/pressures are studied using the first-principles plane wave self-consistent method under the framework of density functional theory. Conclusions based on the phonon dispersion curves, phonon density of states and electronic band structure along with total and projected density of states at finite temperatures/pressures are outlined.

scholarly journals Structural, Electronic, Lattice Dynamic, and Elastic Properties of SnTiO3 and PbTiO3 Using Density Functional Theory

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Shiferaw Kuma ◽  
Menberu Mengesha Woldemariam
Keyword(s):  
Bulk Modulus ◽  
Elastic Properties ◽  
Density Of States ◽  
Elastic Constants ◽  
Density Functional ◽  
Phonon Dispersion ◽  
Electronic Band Structure ◽  
Theoretical Data ◽  
Modern Theory ◽  
Electronic Band

The structural, electronic, and elastic properties of tetragonal phase of SnTiO3 and PbTiO3 are investigated using first principle calculations. The unknown exchange-correlation functional is approximated with generalized gradient approximation (GGA) as implemented in pseudopotential plane wave approach. The convergence test of total energy with respect to energy cutoff and k-point sampling is preformed to ensure the accuracy of the calculations. The structural properties such as equilibrium lattice constant, equilibrium unit cell volume, bulk modulus, and its derivative are in reasonable agreement with the previous experimental and theoretical works. From elastic constants, mechanical parameters such as anisotropy factor A, shear modulus G, bulk modulus B, Young’s modulus E, and Poison’s ratio n are determined by using Voigt–Reuss–Hill average approximation. In addition, Debye temperature and longitudinal and transversal sound velocities are predicted from elastic constants. The electronic band structure and density of states of both compounds are obtained and compared with the available experimental as well as theoretical data. Born effective charge (BEC), phonon dispersion curve, and density of states are computed from functional perturbation theory (DFPT). Lastly, the spontaneous polarization is determined from the modern theory of polarization, and they are in agreement with the previous findings.

scholarly journals Dynamic, Electronic and Optical Properties of Fm3m-HgF2: A DFT Approach

2021 ◽  
Author(s):  
M VAGHELA ◽  
Dhara Raval ◽  
Bindiya Babariya ◽  
P.N. Gajjar
Keyword(s):  
Band Structure ◽  
Charge Density ◽  
Density Of States ◽  
Density Functional ◽  
Phonon Dispersion ◽  
Electronic Band Structure ◽  
Random Phase ◽  
Visible Region ◽  
Optical Parameters ◽  
Electronic Band

In the present work, the cubic structure of HgF2 has been studied using generalized gradient approximation within the framework of density functional theory. Here, the positive phonon frequencies in the phonon dispersion curves show stability of the structure. The elastic constants also satisfy criteria of being kinetically stable material. The B/GH ratio 2.56 of HgF2 indicates its ductile nature. The thermodynamic intrinsic parameters of HgF2 have been calculated using linear response method where the temperature variations of Helmholtz free energy (F), internal energy (E), specific heat at constant volume (Cv) and Debay temperature (ϴD) have been studied. The explanation of the bonding nature is discussed using electronic band structure, density of states and charge density. Here, the presence of the wide valence band gap in electronic band structure and density of states displays the ionic behaviors of HgF2. In addition, the charge density along the [111] plane defines hybridization in between ‘s’, ‘p’ and ‘d’ orbitals in HgF2. The optical parameters of Fm3m-HgF2 were calculated using Random Phase Approximation. Here, the found static refractive index is 1.26. The general optical study showing the trend of being transparent in most of the UV region and fully transparent in the visible region by ionic Fm3m HgF2. Also, it shows significant absorption in the entire UV region and a long absorption tail which extends into the visible region.

Structural, Electronic and Dynamical Properties of Binary Alloy Zr-Al Using Density Functional Theory

2016 ◽  
Vol 1141 ◽  
pp. 204-209
Author(s):  
Hardik L. Kagdada ◽  
Hiral J. Trivedi ◽  
Sharad B. Pillai ◽  
Narayan N. Som ◽  
Prafulla K. Jha
Keyword(s):  
Density Functional Theory ◽  
Density Of States ◽  
Density Functional ◽  
Phonon Dispersion ◽  
Local Density ◽  
Theoretical Data ◽  
Al Alloy ◽  
Electronic Band ◽  
Functional Theory ◽  
End Members

The structural, electronic, dynamical and thermodynamical properties of binary Zr-Al alloy (Zr3Al) with its end members are studied using the first principles calculations based on density functional theory. We have employed the Perdew-Zunger local density approximation as the exchange correlational functional in these calculations. There is a good agreement between present and available and experimental and other theoretical data. The calculated electronic band structure and density of states suggest that the Zr-Al alloy and its end members are metallic in nature consistent with earlier studies. Full phonon dispersion curves and phonon density of states are also calculated which show the dynamical stability of these compounds at zero pressure. The temperature dependence of the thermodynamical functions are also presented.

Ab-Initio Investigation of Strain Effects on the Physical Properties of PdVTe Alloy

2021 ◽  
Author(s):  
Khodja Djamila ◽  
Djaafri Tayeb ◽  
Djaafri Abdelkader ◽  
Bendjedid Aicha ◽  
Hamada Khelifa ◽  
...  
Keyword(s):  
Optical Properties ◽  
Density Of States ◽  
Phonon Dispersion ◽  
Electronic Band Structure ◽  
Debye Model ◽  
Full Potential ◽  
Electronic Band ◽  
Metallic Behavior ◽  
Strain Effects ◽  
Half Metallic

The investigations of the strain effects on magnetism, elasticity, electronic, optical and thermodynamic properties of PdVTe half-Heusler alloy are carried out using the most accurate methods to electronic band structure, i.e. the full-potential linearized augmented plane wave plus a local orbital (FP-LAPW + lo) approach. The analysis of the band structures and the density of states reveals the Half-metallic behavior with a small indirect band gap Eg of 0.51 eV around the Fermi level for the minority spin channels. The study of magnetic properties led to the predicted value of total magnetic moment µtot = 3µB, which nicely follows the Slater–Pauling rule µtot = Zt -18. Several optical properties are calculated for the first time and the predicted values are in line with the Penn model. It is shown from the imaginary part of the complex dielectric function that the investigated alloy is optically metallic. The variations of thermodynamic parameters calculated using the quasi-harmonic Debye model, accord well with the results predicted by the Debye theory. Moreover, the dynamical stability of the investigated alloy is computed by means of the phonon dispersion curves, the density of states, and the formation energies. Finally, the analysis of the strain effects reveals that PdVTe alloy preserves its ferromagnetic half metallic behavior, it remains mechanically stable, the ionic nature dominates the atomic bonding, and the thermodynamic and the optical properties keep the same features in a large interval of pressure.

DFT study of electronic and thermodynamic properties of gold-rich intermetallic compounds, Ce2Au2Cd and CeAu4Cd2

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jyoti Sagar ◽  
Reetu Singh ◽  
Vijay Kumar ◽  
Sanjay Kumar ◽  
Manish P. Singh ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Mechanical Strength ◽  
Intermetallic Compounds ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Debye Model ◽  
Effect Of Temperature ◽  
Mechanical Resistance ◽  
Electronic Band ◽  
High Mechanical Strength

Abstract Gold-rich rare earth intermetallic compounds (viz. Ce2Au2Cd and CeAu4Cd2) show unusual magnetic and physical properties, and they have extensive applications in electronic and mechanical industries due to their good electronic and thermal behavior with high mechanical strength. In the present research article, to take full advantage of technological importance of these materials, we have investigated the structural, electronic and thermodynamic properties of Ce2Au2Cd and CeAu4Cd2 ternary intermetallic compounds using density functional theory (DFT). The electronic band structure and density of state calculations show that Ce-f orbital electrons provide metallic character to both the compounds with strong hybridization of Au-p and Cd-p orbitals at the Fermi level. The effect of temperature has been studied on the various thermodynamic parameters using the quasi-harmonic Debye model. Thermodynamic properties show that CeAu4Cd2 compound has larger mechanical resistance (or high mechanical strength or hardness) and smaller randomness compared to Ce2Au2Cd with respect to temperature.

scholarly journals Structural, Electronic and Vibrational Properties of YAl3(BO3)4

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 545 ◽  
Author(s):  
Aleksandr S. Oreshonkov ◽  
Evgenii M. Roginskii ◽  
Nikolai P. Shestakov ◽  
Irina A. Gudim ◽  
Vladislav L. Temerov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Band Gap ◽  
Density Functional ◽  
Dielectric Material ◽  
Electronic Band Structure ◽  
Vibrational Properties ◽  
Electronic Band ◽  
Functional Theory ◽  
Dynamical Properties ◽  
Indirect Band Gap

The crystal structure of YAl3(BO3)4 is obtained by Rietveld refinement analysis in the present study. The dynamical properties are studied both theoretically and experimentally. The experimental Raman and Infrared spectra are interpreted using the results of ab initio calculations within density functional theory. The phonon band gap in the Infrared spectrum is observed in both trigonal and hypothetical monoclinic structures of YAl3(BO3)4. The electronic band structure is studied theoretically, and the value of the band gap is obtained. It was found that the YAl3(BO3)4 is an indirect band gap dielectric material.

scholarly journals Electronic and Magnetic Properties of Bulk and Monolayer CrSi2: A First-Principle Study

2018 ◽  
Vol 8 (10) ◽  
pp. 1885 ◽  
Author(s):  
Shaobo Chen ◽  
Ying Chen ◽  
Wanjun Yan ◽  
Shiyun Zhou ◽  
Xinmao Qin ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Density Functional ◽  
Phonon Dispersion ◽  
First Principle ◽  
Metallic Behavior ◽  
Functional Theory ◽  
Phonon Dispersion Curves ◽  
Electronic And Magnetic Properties ◽  
Quantum Size ◽  
Spin Polarized

We investigated the electronic and magnetic properties of bulk and monolayer CrSi2 using first-principle methods based on spin-polarized density functional theory. The phonon dispersion, electronic structures, and magnetism of bulk and monolayer CrSi2 were scientifically studied. Calculated phonon dispersion curves indicated that both bulk and monolayer CrSi2 were structurally stable. Our calculations revealed that bulk CrSi2 was an indirect gap nonmagnetic semiconductor, with 0.376 eV band gap. However, monolayer CrSi2 had metallic and ferromagnetic (FM) characters. Both surface and confinement effects played an important role in the metallic behavior of monolayer CrSi2. In addition, we also calculated the magnetic moment of unit cell of 2D multilayer CrSi2 nanosheets with different layers. The results showed that magnetism of CrSi2 nanosheets was attributed to band energy between layers, quantum size, and surface effects.

scholarly journals The Pseudopotential Approach within Density-Functional Theory: The Case of Atomic Metallic Hydrogen

2020 ◽  
Vol 5 (4) ◽  
pp. 74
Author(s):  
Jin Zhang ◽  
Jeevake Attapattu ◽  
Jeffrey M. McMahon
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Phonon Dispersion ◽  
Metallic Phase ◽  
Metallic Hydrogen ◽  
Spectral Functions ◽  
Functional Theory ◽  
Phonon Dispersion Curves ◽  
Pseudopotential Approach ◽  
Critical Temperature Tc

Internal energies, enthalpies, phonon dispersion curves, and superconductivity of atomic metallic hydrogen are calculated. The standard use of pseudopotentials in density-functional theory are compared with full Coulomb-potential, all-electron linear muffin-tin orbital calculations. Quantitatively similar results are found as far as internal energies are concerned. Larger differences are found for phase-transition pressures; significant enough to affect the phase diagram. Electron–phonon spectral functions α2F(ω) also show significant differences. Against expectation, the estimated superconducting critical-temperature Tc of the first atomic metallic phase I41/amd (Cs-IV) at 500 GPa is actually higher.

FIRST-PRINCIPLES STUDIES ON THE ELECTRONIC STRUCTURE OF LuPd2Si2

2009 ◽  
Vol 23 (32) ◽  
pp. 5929-5934 ◽  
Author(s):  
T. JEONG
Keyword(s):  
Band Structure ◽  
First Principles ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Spin Orbit Coupling ◽  
Electronic Band ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Structure Scheme

The electronic band structure of LuPd 2 Si 2 was studied based on the density functional theory within local density approximation and fully relativistic schemes. The Lu 4f states are completely filled and have flat bands around -5.0 eV. The fully relativistic band structure scheme shows that spin–orbit coupling splits the 4f states into two manifolds, the 4f7/2 and the 4f5/2 multiplet.

scholarly journals Ab-initio study of the orthorhombic ndmno3 perovskite

2014 ◽  
Vol 70 (a1) ◽  
pp. C1806-C1806
Author(s):  
Samir Bentata ◽  
Bouabdellah Bouadjemi ◽  
Tayeb Lantri ◽  
Wissem Benstaali
Keyword(s):  
Density Functional ◽  
Electronic Band Structure ◽  
Total Density ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Functional Theory ◽  
Half Metallic ◽  
Generalized Gradient Approximation ◽  
Ferromagnetic Ground State ◽  
Total Density Of States

We investigate the structural, electronic and magnetic properties of the orthorhombic Perovskite oxyde NdMnO3 through density-functional-theory (DFT) calculations using both generalized gradient approximation GGA+U, where U is on-site Coulomb interaction correction. The electronic band structure, the partial and total density of states (DOS) and the magnetic moment are determined. The results show a half-metallic ferromagnetic ground state for the orthorhombic NdMnO3.

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