Browsing by Author "Khenata, R."

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Computational Investigations on Band Structure and Electronic Features of Chromium-Based Carbides and Nitride Cr3px (X = C and N) Through the Fp-Apw Plus Lo Approach
(Academic Press Ltd- Elsevier Science Ltd, 2017) Seddik, T.; Ugur, G.; Soyalp, F.; Khenata, R.; Prakash, Deo; Kityk, I. V.; Verma, K. D.
In this work, we have theoretically investigated the band structure of antiperovskite chromium-based carbides and nitrides Cr3PX (X = C and N) using the first-principles calculation based on the FP-APW+LO method. The principal structural properties i.e., lattice constants (a,b,c) and internal parameters are in accordance with the experimental results. The calculated values of elastic constants indicated that the mechanical strength for both Cr3PC and Cr3PN compounds at (001) plane is higher than the (100) and (010) planes. Moreover, the Cr3PX compounds are expected to be hard materials with ductile nature. In addition, we have found that the FM ground state of herein materials Cr3PC and Cr3PN are energetically favorable with low magnetic moments of about 2.27 and 2.94 AB, respectively, confirming that these are weak ferromagnets. Based on the spin-polarized electronic band structure we have found that both alloys have metallic behavior, such behavior has been shown in the calculated electrical conductivity. We have also estimated other thermoelectric constants like the Seebeck coefficient, thermal conductivity, power factor and electrical resistivity of Cr3PC and Cr3PN compounds. (C) 2016 Published by Elsevier Ltd.
Computational Investigations on Band Structure and Optical Properties of the Besexte1-X Alloys Through the Fp-Lapw Approach
(Elsevier Gmbh, 2017) Hadji, K.; Abdiche, A.; Soyalp, F.; Bin Omran, S.; Khenata, R.
In this paper, we have theoretically explored the structural, electronic and optical properties of the zinc blende structure of ternary alloys using the full-potential linearized augmented plane wave (FP-LAPW) method within the density-functional theory (OFF) as implemented in the Wien2 K code. The electronic properties were computed using the following two approximations: the generalized gradient approximation (GGA) and the Tran-Blaha-modified Becke-Johnson potential (TB-mBJ). The obtained results clearly show that ternary alloys exhibit large and direct band gaps while binary compounds are indirect band gap semiconductors. (C) 2016 Elsevier GmbH. All rights reserved.
Dft-Based Ab Initio Study of the Electronic and Optical Properties of Cesium Based Fluoro-Perovskite Csmf3 (M = Ca and Sr)
(World Scientific Publ Co Pte Ltd, 2012) Harmel, M.; Khachai, H.; Ameri, M.; Khenata, R.; Baki, N.; Haddou, A.; Soyalp, F.
Density functional theory (DFT) is performed to study the structural, electronic and optical properties of cubic fluoroperovskite AMF(3) (A = Cs; M = Ca and Sr) compounds. The calculations are based on the total-energy calculations within the full-potential linearized augmented plane wave (FP-LAPW) method. The exchange-correlation potential is treated by local density approximation (LDA) and generalized gradient approximation (GGA). The structural properties, including lattice constants, bulk modulus and their pressure derivatives are in very good agreement with the available experimental and theoretical data. The calculations of the electronic band structure, density of states and charge density reveal that compounds are both ionic insulators. The optical properties (namely: the real and the imaginary parts of the dielectric function epsilon(omega), the refractive index n(omega) and the extinction coefficient k(omega)) were calculated for radiation up to 40.0 eV.
Elastic, Electronic, Chemical Bonding and Thermodynamic Properties of the Ternary Nitride Ca4tin4: Ab Initio Predictions
(Elsevier Science inc, 2019) Boucenna, S.; Haddadi, K.; Bouhemadou, A.; Louail, L.; Soyalp, F.; Khenata, R.
In order to shed light on the unexplored properties of the ternary nitride Ca4TiN4, we report for the first time the results of an ab initio study of its structural, electronic, elastic, chemical bonding and thermodynamic properties. Calculated equilibrium structural parameters are in excellent concordance with available experimental data. Electronic properties were explored through the calculation of the energy band dispersions and density of states. It is found that Ca4TiN4 has an indirect band gap (Z-Gamma) of 1.625 (1.701) eV using LDA (GGA). Nature of the chemical bonding was studied via Mulliken population analysis and charge density distribution map. It is found that the Ca-N bond is dominantly ionic, whereas the Ti-N one is dominantly covalent. Elastic properties of both single-crystal and polycrystalline phases of the title compound were explored in details using the stain-stress approach. Analysis of the calculated elastic moduli reveals that the title compound is mechanically stable, ductile and elastically anisotropic. Temperature and pressure dependencies of the unit-cell volume, bulk modulus, heat capacities, volume thermal expansion coefficient, Gruneisen parameter and Debye temperature were investigated based on the quasiharmonic Debye model. (C) 2019 Published by Elsevier Inc.
First Principles Calculation of the Structural, Electronic, Optical and Elastic Properties of the Cubic Alxga1-Xsb Ternary Alloy
(Elsevier, 2021) Moussa, R.; Abdiche, A.; Khenata, R.; Soyalp, F.
The aim of this paper is to investigate the structural, electronic, optical and elastic properties of the cubic AlxGa1-xSb ternary alloy with their related binary compounds GaSb and AlSb. The calculations are performed within density functional theory (DFT) using full-potential linearized augmented plane wave (FP-LAPW) method as implemented in Wien2k package. It is found that the lattice parameter of the AlxGa1-xSb ternary alloy shown a non-linear variation with the Aluminum (Al) mole fraction. Beside, the band gap variations with the composition of the ternary alloy exhibit also a small deviation from the Vegard's law, and the obtained results confirm the semiconducting character of the studied materials. Furthermore, the optical properties of the materials are calculated and compared with the theoretical models and with the experimental data found in the literature where a good agreement is observed. The elastic properties of the studied alloys are also determined in this study and they are compared with other works available in the literature.
First-Principle Study of the Structural, Electronic, and Optical Properties of Cubic Innxp1-X Ternary Alloys Under Hydrostatic Pressure
(Walter de Gruyter Gmbh, 2016) Hattabi, I.; Abdiche, A.; Moussa, R.; Riane, R.; Hadji, K.; Soyalp, F.; Khenata, R.
In this article, we present results of the first-principle study of the structural, electronic, and optical properties of the InN, InP binary compounds and their related ternary alloy InNxP1-x in the zinc-blend (ZB) phase within a nonrelativistic full potential linearised augmented plan wave (FP-LAPW) method using Wien2k code based on the density functional theory (DFT). Different approximations of exchange-correlation energy were used for the calculation of the lattice constant, bulk modulus, and first-order pressure derivative of the bulk modulus. Whereas the lattice constant decreases with increasing nitride composition x. Our results present a good agreement with theoretical and experimental data. The electronic band structures calculated using Tran-Blaha-modified Becke-Johnson (TB-mBJ) approach present a direct band gap semiconductor character for InNxP1-x compounds at different x values. The electronic properties were also calculated under hydrostatic pressure for (P = 0.00, 5.00, 10.0, 15.0, 20.0, 25.0 GPa) where it is found that the InP compound change from direct to indirect band gap at the pressure P = 7.80 GPa. Furthermore, the pressure effect on the dielectric function and the refractive index was carried out. Results obtained in our calculations present a good agreement with available theoretical reports and experimental data.
First-Principles Study of Structural, Electronic, and Optical Properties of Cubic Inasxnyp1-X Triangular Quaternary Alloys
(Iop Publishing Ltd, 2017) Hattabi, I.; Abdiche, A.; Soyalp, F.; Moussa, R.; Riane, R.; Hadji, K.; Khenata, R.
In this paper, we investigated the structural, electronic and optical properties of InAs, InN and InP binary compounds and their related ternary and quaternary alloys by using the full potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT). The total energies, the lattice parameters, and the bulk modulus and its first pressure derivative were calculated using different exchange correlation approximations. The local density approach (LDA) and Tran-Blaha modified Becke-Johnson (TB-mBJ) approximations were used to calculate the band structure. Nonlinear variations of the lattice parameters, the bulk modulus and the band gap with compositions x and y are found. Furthermore, the optical properties and the dielectric function, refractive index and loss energy were computed. Our results are in good agreement with the validated experimental and theoretical data found in the literature.
Optoelectronic and Thermoelectric Properties of Zintl Yli3a2 (A = Sb, Bi) Compounds Through Modified Becke-Johnson Potential
(Iop Publishing Ltd, 2016) Seddik, T.; Ugur, G.; Khenata, R.; Ugur, S.; Soyalp, F.; Murtaza, G.; Bin Omran, S.
In the present work, we investigate the structural, optoelectronic and thermoelectric properties of the YLi3X2 (X = Sb, Bi) compounds using the full potential augmented plane wave plus local orbital (FP-APW + lo) method. The exchange-correlation potential is treated with the generalized gradient approximation/local density approximation (GGA/LDA) and with the modified Becke-Johnson potential (TB-mBJ) in order to improve the electronic band structure calculations. In addition, the estimated ground state properties such as the lattice constants, external parameters, and bulk moduli agree well with the available experimental data. Our band structure calculations with GGA and LDA predict that both compounds have semimetallic behaviors. However, the band structure calculations with the GGA/TB-mBJ approximation indicate that the ground state of the YLi3Sb2 compound is semiconducting and has an estimated indirect band gap (Gamma-L) of about 0.036 eV while the ground state of YLi3Bi2 compound is semimetallic. Conversely the LDA/TB-mBJ calculations indicate that both compounds exhibit semiconducting characters and have an indirect band gap (Gamma-L) of about 0.15 eV and 0.081 eV for YLi3Sb and YLi3Bi2 respectively. Additionally, the optical properties reveal strong responses of the herein materials in the energy range between the IR and extreme UV regions. Thermoelectric properties such as thermal conductivity, electrical conductivity, Seebeck coefficient, and thermo power factors are also calculated.
Prediction Study of the Mechanical and Thermodynamic Properties of the (R Sm, Eu, Gd, and Tb) Compounds
(Springer/plenum Publishers, 2013) Mekkaoui, F.; Litimein, F.; Khenata, R.; Merabiha, O.; Bouhemadou, A.; Varshney, D.; Rached, D.
The structural, elastic, and thermodynamic properties of the cubic anti-perovskite (R = Sm, Eu, Gd, and Tb) compounds have been investigated using first principles full-potential augmented-plane wave plus local orbitals (FP-APW+lo) method with the generalized gradient approximation. The ground-state quantities such as the lattice parameter, bulk modulus, and its pressure derivative, as well as elastic constants are estimated. Computed equilibrium lattice constants agree well with the available experimental data. The full set of first-order elastic constants and their pressure dependence, which have not been calculated or measured yet, have been determined. The elastic moduli increase linearly with increasing pressure and satisfy the generalized elastic stability criteria for cubic crystals under hydrostatic pressure. The shear modulus, Young's modulus, and Poisson's ratio are calculated for ideal polycrystalline aggregates. The Debye temperature is estimated from the average sound velocity. From the elastic parameter behavior, it is inferred that cubic anti-perovskites are ductile in nature and that the bonding is predominantly of an ionic nature. Following the quasi-harmonic Debye model, the temperature effect on the lattice constant, bulk modulus, heat capacity, and Debye temperature is calculated reflecting the anharmonic phonon effects.
Pressure Effect on the Structural, Electronic and Optical Properties of the Cubic Triangular Quaternary Bnxasyp1-X Alloys: First Principle Study
(Elsevier, 2018) Hattabi, I; Abdiche, A.; Semari, F.; Khenata, R.; Soyalp, F.
Predicted results of the structural, electronic and optical properties of the cubic zinc-blende phase of BN, BAs and BP binary compounds and their related ternary and quaternary alloys are presented. The density functional theory (DFT) within full potential linearized augmented plan wave (FP-LAPW) is employed. Different exchange correlation approximations were used to calculate the structural properties as well as the total energies, lattice parameters, bulk modulus and its first pressure derivative. The electronic band structures were treated with the local density approach and Tran Blaha modified Beck-Johnson (TB-mBJ) approximation. A quadratic fit of the lattice parameter, bulk modulus and band gap was performed, where a nonlinear variation with the composition x and y is found. Moreover, the optical properties have been investigated, where the dielectric behavior, the refractive index variations and the loss energy were studied. Furthermore, the electronic and optical properties were computed under hydrostatic pressure. Our results showed great agreement with the previous available experimental and theoretical data found in the literature.
Structural, Elastic, Electronic and Optical Properties of Cu3tmse4 (Tm = V, Nb and Ta) Sulvanite Compounds Via First-Principles Calculations
(Amer Scientific Publishers, 2013) Bougherara, K.; Litimein, F.; Khenata, R.; Ucgun, E.; Ocak, H. Y.; Ugur, S.; Bin Omran, S.
The structural and optoelectronic properties of the cubic Cu3TMSe4 (TM = V, Nb and Ta) sulvanite compounds have been calculated using a full-potential augmented plane wave plus local orbitals (FP-APW + lo) method within the density functional theory. The exchange-correlation potential was treated with the generalized gradient approximation of Wu and Cohen (WC-GGA) to calculate the total energy. Moreover, the Engel-Vosko generalized gradient approximation (EV-GGA) and the modified Becke-Johnson potential (TB-mBJ) were also applied for the electronic and optical properties. The ground state properties, including, lattice constants, bulk modulus are in reasonable agreement with the available experimental and theoretical data. The elastic constants C-ij are computed using the total energy variation versus strain technique. The polycrystalline elastic moduli, namely; shear modulus, Young's modulus, Poisson's ratio and anisotropic factor were derived from the obtained single-crystal elastic constants. As a result, brittleness behaviour of these compounds is interpreted via the calculated elastic constants C-ij. The calculations of the electronic band structure show that these compounds have an indirect energy band gap (R-X) and the TB-mBJ approximation yields larger fundamental band gaps compared to those of WC-GGA and EV-GGA. The dielectric function, refractive index, extinction coefficient, reflectivity, and energy loss function were calculated for radiation up to 45 eV.
Structural, Electronic, Optical and Thermodynamic Properties of the Cubic Quadratic Quaternary Alloys Gaxin1-Xasyn1 Insight From Dft Computations
(Elsevier, 2021) Abdiche, A.; Oualdine, A.; Guemou, M.; Khenata, R.; Soyalp, F.; Ahmed, R.; Bin-Omran, S.
In this study, we present our predicted results related to the structural, electronic, and optical properties of Ga(x)In(1-x)AsyN(1-y) quaternary alloys while assessing the associated zinc blende binary and ternary compounds. All calculations are performed by employing the full-potential linearized augmented plane wave plus local orbital method (FP-L(APW + lo)) based on density functional theory (DFT) and implemented in the WIEN2k computational package for crystalline materials. The exchange-correlation energy and potential functional are treated by the local density approximation (LDA) parameterized by Perdew-Wang (PW) and the PBE functional for solids, i.e., PBEsol-GGA, for the calculations of structural parameters, while the Tran-Blaha Becke-Johnson (TB-mBJ) potential approximation combined with PBE-GGA is applied for band structure calculation. The composition-dependent results of the lattice parameters, bulk modulus, and bandgap energy are also studied by performing a quadratic fit, where nonlinear variations in the results are observed. One can note that the bandgap energies are direct for all considered compositions (x, y). Moreover, the dielectric behavior, refractive index, and loss energy are predicted in the context of the optical properties, and the variation in the composition slightly affects the optical stability of the studied alloys. We have also carried out predictions of the thermodynamic properties such as the lattice parameter a(P, T), the Debye temperature theta(D), the heat capacity C-v, and the entropy S using the GIBBS program. To the best of our knowledge, this work represents the first theoretical study on these quaternary alloys and awaits experimental confirmation.
Studying Structural, Electronic and Optical Properties of Zinc-Blende Ga1-Xalxp at Normal and Under Pressure by Means of First Principle
(Institute of Physics Publishing, 2015) Moussa, R.; Abdiche, A.; Khenata, R.; Rai, D.P.; Ahmed, W.K.; Omran, S.B.; Soyalp, F.
Structural, electronic and optical properties of the zinc-blende Ga1-xAlxP ternary alloys with their ordered AlP and GaP binary compounds have been investigated, using the full potential linearized augmented plane wave method in conjunction with the density functional theory. The total energies are carried out to calculate the lattice constant, bulk modulus and its pressure derivative of the zincblende AlP, GaP binary compounds and their corresponding ternary Ga1-xAlxP solid solutions for the compositions (x = 0.25, 0.50 and 0.75). The band gap energies and the optical properties of these materials are investigated at normal pressure condition as well as under high pressure levels. The estimated results obtained from this work are justified, discussed and compared with the experimental data and other available theoretical works. © 2015 IOP Publishing Ltd.
Theory Study of Structural Parameters, Elastic Stiffness, Electronic Structures and Lattice Dynamics of Rbrh3 (R = Sc, Y, La and Lu)
(Elsevier Science Bv, 2012) Bouhemadou, A.; Ugur, G.; Ugur, S.; Soyalp, F.; Khenata, R.; Bin-Omran, S.
Density functional-based method has been used to investigate the systematic trends for structural parameters, elastic stiffness, lattice dynamics and thermal properties of cubic perovskite-type RBRh3 depending on the type of R atoms (R are Sc, Y, La and Lu). The structural parameters, single-crystal elastic constants, directional elastic wave velocities and their pressure dependence are calculated and analyzed in comparison with the available experimental and theoretical data. A set of isotropic elastic parameters and related properties, namely bulk and shear moduli, Young's modulus, Poisson's ratio, Lame's coefficients, average sound velocity. Debye temperature and thermal conductivity are predicted in the frame work of the Voigt-Reuss-Hill approximation for the polycrystalline RBRh3. The correlation between the mechanical properties and electronic structures has been discussed. Using the density-functional perturbation theory (DFPT), the phonon properties of RBRh3 (R = Sc, Y and La) are investigated for the first time. (C) 2011 Elsevier B.V. All rights reserved.