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Abstract: Some physical properties of the cubic perovskites CsXF3 (X = Ca, Sr and Hg) have been investigated using pseudopotential plane-wave method based on the density functional theory. The calculated lattice parameters within GGA and LDA agree reasonably with the available experimental data. The elastic constants and their pressure derivatives are predicted using the static finite strain technique. We derived the bulk and shear moduli, Young''s modulus, Poisson''s ratio and Lamé’s constants for ideal polycrystalline aggregates. The analysis of B/G ratio indicates that CsXF3 (X = Ca, Sr and Hg) are ductile materials. The thermal effect on the volume, bulk modulus, heat capacity and Debye temperature was predicted. [Copyright &y& Elsevier]

Abstract: We have carried out a first-principles density functional study of the structural, elastic and thermodynamic properties for the SnMg2O4, SnZn2O4 and SnCd2O4 cubic normal spinel structures. We have calculated the equilibrium structural parameters: the lattice constant and internal structural parameter. These results agree very well with experimental data. We have investigated the zero-pressure single-crystal and polycrystalline elastic constants and their related properties, confirming prior theoretical results for SnMg2O4 and predicting values for SnZn2O4 and SnCd2O4. The pressure dependence of the elastic constants Cij can be fit by a straight line over the range 0–30GPa. Thermal and pressure effects on some macroscopic properties of SnMg2O4, SnZn2O4 and SnCd2O4 are predicted using the quasi-harmonic Debye model in which the lattice vibrations are taken into account. [Copyright &y& Elsevier]

Abstract: Structural, elastic, electronic and magnetic properties of Mn3ZnC and Mn3GeC are investigated via ab initio calculations. Total energy calculations show that the ferromagnetic state is energetically more stable than the non-magnetic state at equilibrium volume. No found imaginary phonon frequency in the whole Brillouin zone for the two compounds supports their dynamical stability. The elastic parameters are predicted. The electrical conductivity is assured by the Mn-d electrons. The total moment comes principally from the transition metal Mn in both compounds. The magnetic moment of the Mn atom decrease considerably when the Zn atom is substituted by the Ge one. [Copyright &y& Elsevier]

Abstract: Density functional calculations are performed to study the structural, electronic and optical properties of technologically important B x Ga1−x As ternary alloys. The calculations are based on the total-energy calculations within the full-potential augmented plane-wave (FP-LAPW) method. For exchange-correlation potential, local density approximation (LDA) and the generalized gradient approximation (GGA) have been used. 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 electronic band structure, density of states for the binary compounds and their ternary alloys are given. The dielectric function and the refractive index are also calculated using different models. The obtained results compare very well with previous calculations and experimental measurements. [Copyright &y& Elsevier]

Abstract: The structural, elastic, thermodynamic, electronic and magnetic properties of ferromagnetic tetragonal PrNi2Si2 and PrNi2Ge2 compounds have been calculated using the full-potential linear muffin-tin orbital (FP-LMTO) method. The exchange–correlation potential is treated within the local spin density approximation of Perdew and Wang (LSDA–PW). Moreover, we have added the Coulomb interaction U to improve the electronic band structure calculations and the magnetic properties. The calculated structural parameters are in good agreement with the experimental data. The elastic constants Cij are predicted using the total energy variation versus strain technique. The polycrystalline elastic moduli, namely; shear modulus, Young’s modulus, Poisson’s ratio, sound velocities and Debye temperature are derived from the obtained single-crystal elastic constants. Ductility behavior of these compounds is interpreted via the calculated elastic constants Cij . Electronic and bonding properties are discussed from the calculations of band structure and density of states. The thermodynamic properties are predicted through the quasi-harmonic Debye model, in which the lattice vibrations are taken into account. The variation of the bulk modulus, lattice constant, heat capacities and Debye temperature with pressure and temperature are successfully obtained. [Copyright &y& Elsevier]

Abstract: 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, Lamé’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. [Copyright &y& Elsevier]

Abstract: The structural and electronic properties of cubic zinc blende BN, BP, AlN and AlP compounds and their B x Al1−x N y P1−y quaternary alloys, have been calculated using the non relativistic full-potential linearized-augmented plane wave FP-LAPW method. The exchange-correlation potential is treated with the local density approximation of Perdew and Wang (LDA-PW) as well as the generalized gradient approximation (GGA) of Perdew–Burke and Ernzerhof (GGA-PBE). The calculated structural properties of BN, BP, AlN and AlP compounds are in good agreement with the available experimental and theoretical data. A nonlinear variation of compositions x and y with the lattice constants, bulk modulus, direct and indirect band gaps is found. The calculated bowing of the fundamental band gaps is in good agreement with the available experimental and theoretical value. To our knowledge this is the first quantitative theoretical investigation on B x Al1−x N y P1−y quaternary alloy and still awaits experimental confirmations. [Copyright &y& Elsevier]

Abstract: We have investigated the structural, elastic, electronic, optical and thermodynamic properties of the cubic spinel CdAl2O4 using accurate ab initio calculations. Computed equilibrium structural parameters are in good agreement with the available experimental data. Single-crystals elastic parameters are calculated for pressure up to 30GPa using a conserving-volume total energy-strain method. Isotropic elastic parameters for ideal polycrystalline CdAl2O4 aggregates are computed in the framework of the Voigt–Reuss–Hill approximation. Result for band structure using the Engel–Vosko scheme of the GGA shows a significant improvement over the common GGA functionals. Optical spectra have been calculated for the energy range 0–30eV. The peaks and structures in the optical spectra are assigned to interband transitions. Pressure dependence of the band gaps, static dielectric constant and static refractive index are also investigated. Pressure and thermal effects on some macroscopic properties are predicted using the quasi-harmonic Debye model. [Copyright &y& Elsevier]

Abstract: An accurate ab initio full potential linear muffin-tin orbital method has been used to investigate the structural, electronic and optical properties of BP, BAs and their (BP) n /(BAs) n superlattices (SLs). The exchange-correlation potential is treated with the local density approximation of Perdew and Wang (LDA-PW). The calculated structural properties of BP and BAs compounds are in good agreement with available experimental and theoretical data. It is found that BP, BAs and their alloys exhibit an indirect fundamental band gap. The fundamental band gap decreases with increasing the number of monolayer n. The optical properties show that the static dielectric constant significantly decreases in superlattices compared to their binary compounds. [Copyright &y& Elsevier]

Abstract: We report the systematic trends for structural, band structure, total density of states, dielectric function, reflectivity, refractive index and loss function for the family of spinel oxides ZnB 2O4 depending on the type of B element (B are Al, Ga and In). The full-potential augmented plane wave plus local orbitals method based on the density functional theory is used within the generalized gradient approximation (GGA). Moreover, the alternative form of GGA proposed by Engel and Vosko (GGA-EV) is also used for the band structure calculations. The optimized zero pressure geometrical parameters: the unit cell length a, the internal coordinate u, the bulk modulus B and the pressure derivative of the bulk modulus B′ are in agreement with the available experimental data. Results obtained for the band structure using GGA-EV show a significant improvement over other theoretical works and are closer to the experimental data. Calculations of optical spectra have been performed for the energy range 0–35eV. The peaks and structures in the optical spectra are assigned to interband transitions. Pressure dependence of the band gaps, static dielectric constant and static refractive index are also investigated. [Copyright &y& Elsevier]

Abstract: The structural, elastic, electronic, and optical properties of cubic spinel MgIn2S4 and CdIn2S4 compounds have been calculated using a full relativistic version of the full-potential linearized-augmented plane wave with the mixed basis FP/APW+lo method. The exchange and correlation potential is treated by the generalized-gradient approximation (GGA). Moreover, the Engel–Vosko GGA formalism is also applied to optimize the corresponding potential for band structure calculations. The ground state properties, including the lattice constants, the internal parameter, the bulk modulus, and the pressure derivative of the bulk modulus are in reasonable agreement with the available data. Using the total energy-strain technique, we have determined the full set of first-order elastic constants C ij and their pressure dependence, which have not been calculated or measured yet. The shear modulus, Young’s modulus, and Poisson’s ratio are calculated for polycrystalline XIn2S4 aggregates. The Debye temperature is estimated from the average sound velocity. Electronic band structures show a direct band gap (Г–Г) for MgIn2S4 and an indirect band gap (K–Г) for CdIn2S4. The calculated band gaps with EVGGA show a significant improvement over the GGA. The optical constants, including the dielectric function ε(ω), the refractive index n(ω), the reflectivity R(ω), and the energy loss function L(ω) were calculated for radiation up to 30eV. [ABSTRACT FROM AUTHOR]

Abstract: We have performed accurate ab initio total energy calculations using the full-potential linear augmented plane wave plus local orbitals method with the local density approximation for the exchange–correlation potential to investigate the systematic trends for structural and elastic properties of the cubic LaFe4A12 skutterudites’ family depending on the type of A pnicogen atom (A stands for P, As and Sb). The calculated equilibrium lattice constants and internal free parameters are in good agreement with the experimental results. For the first time, the numerical estimates of the independent elastic constants and their pressure dependence are performed using the total energy variation as function of strain technique. Isotropic elastic parameters and related properties, namely bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, Lamé’s coefficients, average sound velocity and Debye temperature, are estimated in the framework of the Voigt–Reuss–Hill approximation for ideal polycrystalline LaFe4A12 aggregates. [Copyright &y& Elsevier]

Abstract: Ab initio study of structural, elastic, electronic and optical properties of the cubic spinel oxide SnMg2O4 has been reported using the pseudo-potential plane-wave method within the local density approximation and the gradient generalized approximation for the exchange and correlation potential. Computed lattice constant and internal free parameters are in good agreement with the available experimental results. The elastic constants and their pressure dependence are predicted using the static finite strain technique. A linear pressure dependence of the elastic stiffnesses is found. A set of isotropic elastic parameters and related properties, namely bulk and shear moduli, Young’s modulus, Poisson’s ratio, Lamé’s coefficients, average sound velocity and Debye temperature are numerically estimated in the frame-work of the Voigt–Reuss–Hill approximation for SnMg2O4 polycrystalline. Band structure shows that SnMg2O4 has a direct band gap (Г–Г), which increases with increase in pressure. Density of states and Mulliken population analysis show that the Mg–O bond is typically covalent due to the O-2p and Mg-2p states hybridizations. In order to understand the optical properties of SnMg2O4, the dielectric function, optical reflectivity, refractive index, extinction coefficient and electron energy loss function are calculated for radiation up to 40eV. The pressure dependence of the zero-frequency limit of the real part of the dielectric function ε 1(0) and of the refractive index n(0) has been investigated. This is the first quantitative theoretical prediction of the elastic, electronic and optical properties of the SnMg2O4 compound, and it still awaits experimental confirmation. [ABSTRACT FROM AUTHOR]

We report and discuss the results of a detailed ab initio investigation of the structural, elastic, electronic and optical properties of a new layered perovskite-type oxyfluoride: CsSrNb 2 O 6 F. The calculated ground state lattice parameters are in excellent agreement with the available experimental counterparts. The six predicted distinct single-crystal elastic constants satisfy the mechanical stability criteria. From the calculated single-crystal elastic constants, a set of related properties, viz., the bulk modulus, shear modulus, Young's modulus, anisotropic and isotropic sound velocities, elastic anisotropy, malleability and Debye temperature, are determined. The title compound is found to be ductile with strong elastic anisotropy. Considering that the measured values are always determined with uncertainties of various origins, one can state that the calculated fundamental indirect bandgap value of ~2.9 eV and the onset of direct optical transitions at ~3.6 eV are in acceptable agreement with a prior measurement giving a bandgap of ~3.4 eV. Particular attention has been given to the bonding properties and distribution of the electron density in the space between the crystal lattice ions through the calculation of density of states diagrams, bond lengths and the charge density distribution. The linear optical parameters of the considered compound, including the complex dielectric function, absorption coefficient, refractive index and optical reflectivity, are predicted for incident electromagnetic radiation polarized parallel to the [100] and [001] crystallographic directions. It is noted that CsSrNb 2 O 6 F exhibits a strong optical anisotropy. [ABSTRACT FROM AUTHOR]

We report results of a detailed first-principles study of physical parameters associated with the structural, electronic, optical and elastic properties of the ternary gallium-arsenides Sr 3 GaAs 3 and Ba 3 GaAs 3. Calculated equilibrium structural parameters are in excellent agreement with the available experimental counterparts, providing evidence of the reliability of the reported results. Monocrystalline elastic constants are numerically estimated and analyzed. From the monocrystalline elastic constants, a set of related properties, viz. mechanical stability, anisotropic sound velocities, polycrystalline elastic properties, including bulk modulus, shear modulus, Young's modulus, Poisson's ratio, average sound velocity and Debye temperature, are deduced. Crystal direction dependences of the linear compressibility and Young's modulus are analyzed and visualized by plotting their spatial distributions. From analysis of the energy band dispersions, it is found that the title compounds are semiconductors with direct band gaps positioned in the visible sunlight spectrum in the energy window 1.271 – 1.285 eV. Origins of the electronic states composing the energy bands are determined using the PDOS diagrams. Effective masses of holes and electrons are numerically evaluated at the valence band and conduction band extremes towards the three major crystalline directions. Anisotropies of the hole and electron effective masses are visualized by plotting their dependencies on the crystalline direction. Frequency-dependent linear optical parameters are predicted in an energy window from 0 eV to 14 eV for incident electromagnetic radiation polarized parallel to the three principal crystalline directions. [Display omitted] • The fundamental physical properties of Sr 3 /Ba 3 GaAs 3 are explored. • They are mechanically stable with moderate stiffness and a significant elastic anisotropy. • They are direct band gap semiconductors with mixed covalent-ionic bond characters. • They possess a high absorption band from the visible spectrum to Near-UV. [ABSTRACT FROM AUTHOR]

In this paper, we present the results of a detailed computational study of the structural, electronics, optical, thermodynamic, and thermoelectric properties of the AgXO 2 (X = In, Y) materials with delafossite-type structure, by using the "full-potential linearized augmented plane wave (FP-LAPW)" method. The calculated structural parameters of the title compounds are in excellent agreement with the available theoretical data. We have explored the dynamical stability of the AgXO 2 compounds by investigating the phonon dispersion curves. The optoelectronic characteristics of the studied compounds were accurately described at the level of the "Trans Blaha modified Becke-Johnson (TB-mBJ)" approach to model the exchange-correlation potential. On the other hand, the optical characteristics of the AgInO 2 and AgYO 2 thin films were investigated in the wavelength range 200–750 nm for three different thicknesses: 300, 600 and 1300 nm on a transparent substrate (glass: n glass = 1. 5, k glass = 0). Thermodynamic and thermoelectric properties of the considered compounds were predicted by employing the "quasi-harmonic Debye model" and the Boltzmann transport theory. [ABSTRACT FROM AUTHOR]

We have performed comprehensive DFT-based ab initio calculations of the structural parameters, elastic constants and related properties, electronic structures and optical constants of new quaternary diamond-like compounds, Li 2 HgMS 4 (M = Si, Ge and Sn), which are novel promising infrared nonlinear optical materials. Both the GGA-PBEsol and TB-mBJ functionals were used to describe the exchange-correlation interactions. The spin-orbit coupling was incorporated to account for relativistic effects. The optimized structural parameters, viz., lattice parameters and atomic position coordinates, are in very good agreement with the experimental counterparts. The full set of anisotropic single-crystal elastic constants were predicted through the stress-strain technique and the isotropic polycrystalline elastic moduli and related physical parameters were predicted via the Voigt–Reuss–Hill approximation. The elastic anisotropy was characterized through several different anisotropic indexes. Calculated electronic band structures and density of states diagrams show that the studied compounds are wide direct bandgap semiconductors. The calculated bandgaps, ranging from 2.65 eV (for the Sn compound) to 3.23 eV (for the Si compound), are in acceptable agreement with the available experimental counterparts. The energy-dependent anisotropic linear optical coefficients, viz., complex dielectric function, complex refractive index, reflectivity and energy-loss function, were determined and discussed. • The unexplored fundamental physical properties of Li 2 HgMS 4 were studied. • They are soft, easily compressible and possess a significant elastic anisotropy. • It is shown that they are wide direct band gap semiconductors. • They possess a spread high absorption band in the UV region. [ABSTRACT FROM AUTHOR]

Structural parameters, elastic constants, electronic structure and optical functions of the ternary tetragonal chalcogenides KAlTe 2 and KInTe 2 are predicted via ab initio calculations. The calculated structural parameters and interatomic distances agree very well with the existing experimental results. The computed band structures show that the two studied materials are semiconductors with indirect band-gaps. The computed partial density of states diagrams, charges transfer and distribution of charge density show that the interatomic bonds are mainly of a covalent nature. The calculated elastic constants indicate that the title compounds are mechanically stable and elastically strongly anisotropic. The calculated optical spectra for both explored compounds exhibit a significant optical anisotropy. Both compounds have a low absorption in the visible range compared to the infrared (IR) domain. The refractive index spectrum of KInTe 2 is more anisotropic than that of KAlTe 2. [ABSTRACT FROM AUTHOR]

In this paper, we present and discuss the results of first-principles calculations of the structural, electronic, optical, elastic and thermodynamic properties of the monoclinic quaternary nitride Ba 3 Ca 2 Si 2 N 6. A comparison between the computed crystal structure parameters and the corresponding experimental counterparts shows a very good agreement between them. The elastic constants were evaluated numerically for the monocrystalline and polycrystalline Ba 3 Ca 2 Si 2 N 6 using the strain–stress approach. The predicted elastic constants demonstrate that Ba 3 Ca 2 Si 2 N 6 is soft, ductile and mechanically stable. Ba 3 Ca 2 Si 2 N 6 shows a strong anisotropic behavior of the elastic and structural properties. The calculated band structure reveals a semiconductor character of Ba 3 Ca 2 Si 2 N 6. The spectra of the macroscopic linear optical functions, namely the complex dielectric function, reflection coefficient, energy loss of electrons, absorption coefficient and complex refractive index, were calculated and discussed. The quasi-harmonic Debye model was used to explore the temperature and pressure dependencies of certain macroscopic physical parameters for Ba 3 Ca 2 Si 2 N 6. [ABSTRACT FROM AUTHOR]

In this paper, we present and discuss temperature and doping effects on the electrical and thermal transport properties of SrIn 2 P 2 Zintl phase along the [100] and [001] crystallographic directions. The calculations were performed by using the full-potential linearized augmented plane wave method in conjunction with Boltzmann's transport theory and Bardeen-Shockley's deformation potential with the carrier relaxation time and effective mass approximations. We calculated the band effective masses inside two energy windows of 125 meV; one above the fundamental conduction band minimum (FCBM) and the second below the valence band maximum (VBM). The calculated band effective masses exhibit a noticeable anisotropy and demonstrate that the n -type SrIn 2 P 2 transport properties are better than those of the p -type one over the considered charge-carrier concentration range at room-, intermediate- and high-temperature, due to the proximity of the secondary conduction band minimums to the FCBM (∼58 meV). The n -type SrIn 2 P 2 has a considerable Seebeck coefficient (429 μV/K), an extremely low electrical resistivity (0.90 mΩcm), and a relatively small lattice thermal conductivity (1.12 Wm−1K−1), which yield a figure of merit ZT of 0.87 for an electron concentration of 3.0 × 1019 cm−3 at 900 K. These results make SrIn 2 P 2 a hopeful n -type thermoelectric material if we can further reduce its lattice thermal conductivity. • Transport properties of the layered SrIn 2 P 2 Zintl compound have been predicted. • SrIn 2 P 2 exhibits anisotropic intrinsic and extrinsic transport properties. • It has a low electrical resistivity and a small lattice thermal conductivity. • It has a ZT of 0.87 for the n -type at 900 K and an optimal doping of 3.0 × 1019 cm−3. [ABSTRACT FROM AUTHOR]

Structural, elastic, electronic, and optical properties of BaIn2P2 are determined using a pseudopotential plane-wave method in the framework of DFT within the generalized gradient approximation. [ABSTRACT FROM AUTHOR]

We explored the pressure-induced structural phase transitions and elastic properties of AuMTe 2 (M = Ga, In) using the full-potential linearized augmented plane wave method within the framework of density functional theory, applying both generalized gradient and local density approximations. Thermodynamic properties were further assessed through the quasi-harmonic model. We determined the transition pressures for the phase shift from the chalcopyrite structure to the NaCl rock-salt phase in both AuGaTe 2 and AuInTe 2 . Additionally, we calculated and analyzed mechanical properties, such as bulk modulus, shear modulus, Young's modulus, Poisson's ratio, elastic anisotropy, ductility versus brittleness, and hardness for the polycrystalline forms of AuMTe 2 (M = Ga, In). The study also examined how temperature and pressure affect the Debye temperature, heat capacities, thermal expansion, entropy, bulk modulus, Grüneisen parameter, and hardness, utilizing the quasi-harmonic Debye model.

Context: In this work, a comprehensive study concerning the physical properties of ternary alloys system (AlP 1-x Bi x ) at different concentrations is presented. The obtained results from our first-principle calculations are compared with previously reported studies in the literature and discussed in detail. Our computed results are found in a nice agreement where available with earlier reported results. Electronic band structures at the above-mentioned concentrations are also determined. Likewise, the impact of the varying temperature and pressure on Debye temperature, heat capacity, and entropy is analyzed as well. Furthermore, elastic constants and related elastic moduli results are also computed. Our results show that alloys are stable and found to be in brittle nature. This is the first quantitative study related to ternary alloys (AlP 1-x Bi x ) at mentioned concentrations. We soon expect the experimental confirmation of our predictions., Method: The calculations are performed, at concentrations x=0.0, 0.25, 0.5, 0.75, and 1.0 by using the "full potential (FP) linearized (L) augmented plane wave plus local orbital (APW+lo) method framed within density functional theory (DFT)" as recognized in the "WIEN2k computational code". The "quasi-harmonic Debye model" approach is employed to determine the thermal properties of the title alloys., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

We present the magnetic and optical properties of various combinations of ordered spin state configurations between low-spin (LS) state, intermediate-spin (IS) state, and high-spin (HS) state of LaCoO(3) . In this study, we use the state-of-the-art first principles calculations based on generalized gradient (GGA) + Hubbard U approach. The excited-state properties of different spin configurations of LaCoO(3) such as the X-ray absorption spectra, optical conductivity, reflectivity, and electron energy loss are calculated. We have demonstrated that the optical spectra results can be used for analyzing the spin state of Co(3+) ion. The first specie is the local excitation of IS cobalt ions in the LS ground state. The second excitation leads to the stabilization of the mixed IS/HS Co(3+) metallic state. At low temperature, the comparison between O 2p and Co 3d projected density of states with the experimental valence band spectra indicates significant IS Co(3+) ions and this is in sharp contrast to the HS state which is negligible. The line shape of O 2s and Co 3d core level spectra are well reproduced in this study. The present results are in excellent agreement with the available experimental data. The variation in the spectra of different configurations of LaCoO(3) suggests a changing in the spin state as the temperature is enhanced from 90 to 500 K., (Copyright © 2011 Wiley Periodicals, Inc.)