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the chalcopyrite alloys Cu1–xNaxTlSe2, with x = 0.00, 0.25, and 0.50 were studied through density functional theory calculations. The Wu–Cohen generalized gradient and the Tran–Blaha modified Becke–Johnson approximations have been employed to describe the exchange–correlation potential. Energy band structure analysis reveals that CuTlSe2 is a semi-metal, while Cu0.25Na0.75TlSe2 and Cu0.50Na0.50TlSe2 alloys are semiconductors with gaps of approximately 0.17 eV and 0.35 eV, respectively. The total and partial densities of states were calculated and discussed. Examining the charge density, we point out the formation of the Na–Se ionic bond when Cu is replaced by the Na atom, which is responsible for the metal–semiconductor transition in the Cu1–xNaxTlSe2 alloys. Moreover, variations of the Seebeck coefficient, electrical conductivity, electronic and lattice thermal conductivity, power factor, and figure of merit of the Cu1–xNaxTlSe2 alloys with temperature and chemical potential were explored. The obtained results show that the value of the figure of merit increases when doping CuTlSe2 with sodium to reach 0.46 and 0.87 for p-type Cu0.75Na0.25TlSe2 and n-type Cu0.50Na0.50TlSe2, respectively the chalcopyrite alloys Cu1–xNaxTlSe2, with x = 0.00, 0.25, and 0.50 were studied through density functional theory calculations. The Wu–Cohen generalized gradient and the Tran–Blaha modified Becke–Johnson approximations have been employed to describe the exchange–correlation potential. Energy band structure analysis reveals that CuTlSe2 is a semi-metal, while Cu0.25Na0.75TlSe2 and Cu0.50Na0.50TlSe2 alloys are semiconductors with gaps of approximately 0.17 eV and 0.35 eV, respectively. The total and partial densities of states were calculated and discussed. Examining the charge density, we point out the formation of the Na–Se ionic bond when Cu is replaced by the Na atom, which is responsible for the metal–semiconductor transition in the Cu1–xNaxTlSe2 alloys. Moreover, variations of the Seebeck coefficient, electrical conductivity, electronic and lattice thermal conductivity, power factor, and figure of merit of the Cu1–xNaxTlSe2 alloys with temperature and chemical potential were explored. The obtained results show that the value of the figure of merit increases when doping CuTlSe2 with sodium to reach 0.46 and 0.87 for p-type Cu0.75Na0.25TlSe2 and n-type Cu0.50Na0.50TlSe2, respectively

The first-principle calculations of density functional theory were used to study the structural, electronic, magnetic, mechanic, and half-metallic behavior of Y2MnZ (Z = Al, Ga, In) within the spin generalized gradient approximation. These compounds can be experimentally synthesized due to their negative values of the calculated formation energies. Our calculations indicate that they are more stable in Cu2MnAl-type structure. The Hg2CuTi-type structure displays half-metallic characteristic with 100% spin polarization at the Fermi level. The value of calculated magnetic moment has an integer value of 2μB for Y2MnZ (Z = Al, Ga, In) in the Hg2CuTi-type structure which well matches with magnetic moments predicted from Slater–Pauling rule. Therefore, the Y2MnZ (Z = Al, Ga, In) in the Hg2CuTi-type structure is predicted to be a candidate for possible spintronics applications.

The structural, phase stability, elastic and electronic properties of Sb-doped BBi have been systematically investigated in the zinc blende phase by means of the first-principle approach based on the density functional theory (DFT). The structural and elastic properties were computed by using the generalized gradient approximation proposed by Wu and Cohen (WC-GGA). Specifically, the calculated basic structural parameters, such as the lattice constant and bulk modulus, are in good agreement with the existing experimental measurements and theoretical calculations. The phase stability of BBi1-xSbx alloys in the zinc blende and rock salt phases has been investigated with the determination of the transition pressures (Pt) from the zinc blende (B3) to the rock salt (B1) phase. The electronic band structures were determined using the Tran–Blaha-modified Johnson functional. Furthermore, we investigated the mechanical properties and anisotropic behavior of the BBi1-xSbx alloys.

We have studied the doping concentration dependence of the thermoelectric (TE) properties for the n- and p-doped CaIn2P2 layered Zintl phase at two fixed temperatures: T = 600 and 900 K through fir...

In this paper, we have studied the impact of the pressure on the magnetic, elastic, and mechanical properties of the cobalt Co and cobalt hydride CoH using the full-potential linearized augmented plane wave (FPLAPW) method within the generalized gradient approximation (GGA). The obtained results show an excellent agreement with the available experimental and theoretical data at zero pressure, whereas for pressures up to 20 GPa, the results obtained are considered the first quantitative theoretical prediction for cobalt and cobalt hydride. The calculated electronic properties and spin magnetic moment proved that the metallic and ferromagnetic aspects are preserved for both Co and CoH under different pressure values. Moreover, the results achieved for the elastic constants Cij and the mechanical properties (bulk modulus B, shear modulus G, Young’s modulus Y, and Poisson’s ratio ν) verified that studied systems are mechanically stable under the tested pressure range. Besides, the discussed results reveal the enhancement in the ductility for both Co and CoH with increasing pressure.

In this work, we present our predictions on lithium niobate LiNbO3 concerning its structural, electronics, thermal and optical properties. These predictions are done by means of first-principles ca...

We performed ab initio calculations to study the structural and optoelectronic properties of simple and slab phase TaNO using density functional theory (DFT), in which the full potential augmented plane wave (FP-LAPW) method was implemented using the computational code Wien 2k. The modified Becke-Johnson potential (mBJ-GGA) was used for these calculations. The calculated band structure and electronic properties revealed an indirect bandgap for simple TaNO (3.2 eV) and a direct bandgap for slab TaNO (1.5 eV). The interband electronic transitions were investigated from the band structure, and transition peaks were observed from the imaginary part of the dielectric function. These transitions are due to Ta-p, N-p and O-p orbitals for simple TaNO and Ta-p, N-s as well as O-p orbitals for slab TaNO. The plasmon energy was related to the main peak of the energy loss function, which was approximately 10 eV. The static value of the dielectric constant and the refraction were close to the experimental values. In general, slab TaNO shows different properties and is more suitable for optoelectronic applications due to direct bandgap.

A theoretical study of the structural, elastic, electronic, optical, magnetic, and thermoelectric properties of the newly synthetized diamond-like quaternary semiconductor CuMn2InSe4 was carried out in this paper. The calculated equilibrium structural parameters are in excellent agreement with available experimental data. The single-crystal and polycrystalline elastic moduli were predicted using energy strain technique. Electronic properties, including band energy dispersion, total and projected densities of states, and charge distribution map, were calculated and analyzed. Total and local magnetic moments were determined. Linear optical functions were predicted from the calculated band structure. We studied the chemical potential dependence of the thermoelectric parameters, including Seebeck coefficient, electrical conductivity, thermal conductivity, and power factor. The maximum power factor and the corresponding chemical potential are estimated. The obtained results were compared with available ones.

The zone-center phonon frequencies and the elastic properties of six ternary chalcopyrite compounds represented by ABSe2 (A = Cu and Ag; B = Al, Ga and In) are systematically calculated by using the rigid ion model. In the present paper, we calculate four bond-stretching and three bond-bending interactions, along with three effective dynamical charges. The calculated results are compared and found to be in fairly good agreement with the available experimental and theoretical results. The elastic anisotropy of the studied compounds is analyzed and visualized by plotting three-dimensional surfaces representing the directional dependences of Young's modulus.

Density functional FP-LAPW+lo method calculations were performed to explore the structural, electronic, optical, elastic, thermoelectric and thermodynamic properties of the spinel oxides ZnRh2O4 and CdRh2O4. The exchange-correlation potential were described using the GGA-PBEsol and TB-mBJ functionals. As the first step, the optimized structural parameters, including the lattice parameter and atomic coordinates, were determined. Electronic band structure, atomic-resolved l-projected densities of electronic states and photon energy dependence of the linear optical functions were computed. It is found that both investigated compounds are indirect band gap semiconductors. The band gap results from the splitting of the R h : 4 d 6 states into occupied R h : 4 d − t 2 g 6 states, which form the valence band maximum (VBM), and the empty states R h : 4 d − e g 0 , which form the conduction band minimum (CBM), owing to the octahedral substantial crystal-field. The electronic interband transitions responsible of the structures in the optical spectra were specified. Single-crystal and polycrystal elastic moduli, wave sound velocities, Debye temperature, Pugh's indicator and indexes of elastic anisotropy were numerically estimated using total energy versus strain. FP-LAPW+lo band structure in combination with the standard Boltzmann transport theory were employed to calculate the thermoelectric parameters, including Seebeck coefficient, electrical and thermal conductivities and figure of merit. It is found that the title compounds are potential candidates for thermoelectric applications if one can further reduce their thermal conductivities via some techniques. FP-LAPW+lo approach in combination with the quasi-harmonic Debye model was employed to study temperature and pressure dependences of some macroscopic physical parameters. Our obtained results in the present work are discussed in comparison with the available experimental and theoretical data. The calculated results show a good agreement with the available experimental and theoretical results.

To investigate the structural, elastic and electronic properties of the tetragonal inter-alkali metal chalcogenides CsNaX (X = S, Se, and Te), we have applied the full-potential linearized augmented plane-wave plus local orbital (FP-LAPW + lo) method within the density functional theory (DFT) framework. For the description of the exchange-correlation potential, the Wu-Cohen generalized gradient approximation (WC-GGA) was employed. Furthermore, the generalized gradient approximation of Engel and Vosko (EV-GGA) and Tran-Blaha modified Becke-Johnson (TB-mBJ) potential were also applied to obtain reliable results for the electronic properties of CsNaX compounds. Our optimized equilibrium structural parameters are in good agreement with experimental measurements where available. The Young's modulus, bulk modulus, shear modulus, Poisson's ratio, Pugh's ratio, acoustic velocities and Debye temperature were derived from our estimated elastic constants C i j . It is found that all the considered compounds are mechanically stable and ductile in nature. In addition, the elastic anisotropy of the examined compounds was studied by visualizing the directionally dependent Young's modulus, shear modulus and compressibility, as well as by calculating some elastic anisotropy indices. Electronic properties, such as the band structure, density of states and the charge density, were analyzed in detail. Calculated band structures show that the studied materials are semiconductors with indirect band gaps (Z-Γ).

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.

The structural stability and optoelectronic properties of the ternary Ba1−xBexS alloys along with the pure binary compounds BaS and BeS in the rock-salt (B1) and zinc-blende (B3) phases were investigated by the density functional theory (DFT) within the full-potential linearized augmented plane wave (FP-LAPW) method implemented in the Wien2k package. The generalized gradient approximation of Wu and Cohen (WC-GGA) was used for the exchange-correlation potential (Vxc) to compute the equilibrium structural parameters, lattice constant (a), and bulk modulus (B). In addition to the GGA approach, the modified Becke-Johnson potential of Tran and Blaha (TB-mBJ) scheme coupled with the spin-orbit interaction was used to calculate the band gap energies. Results reveal that BaS, Ba0.75Be0.25S, and Ba0.5Be0.5S compounds are stable in the rock-salt phase, while Ba0.25Be0.75S and BeS are found to be stable in the zinc-blende phase. The computed results for the band structures and optical constants are compared with other available theoretical calculations and experimental measurements.

In this study, the full potential linearized augmented plane wave method with the GGA approximation was employed to study the structural, elastic, electronic and thermal properties of the novel intermetallic $$\hbox {REPt}_4\hbox {In}_{4}$$ (RE $$=$$ Eu, Gd, Tb, Dy, Ho) compounds. Our findings demonstrate that the equilibrium lattice parameters are in good agreement with the available experimental measurements. The elastic constants ( $$C_\mathrm{ij}$$ ) were also calculated to understand the mechanical properties and structural stability of the compounds. Furthermore, the density of states and the charge density distributions of the compounds were calculated to understand the nature of the bonding in the material. Our analysis of the calculated values of the Poisson’s ratio and the B/G ratio shows their ductile structure. Additionally, the temperature-dependent thermodynamic parameters are computed by the quasi-harmonic Debye model in the range of 0–600 K, where the primitive cell volume and thermal expansion coefficients have been obtained successfully. Consequently, this study on the structural, elastic, bonding and thermal properties of $$\hbox {REPt}_4\hbox {In}_4$$ intermetallic compounds demonstrate that these compounds can be used as potential candidates in the domain of energy storage and electronic devices.

The full potential linearized augmented plane wave (FP-LAPW) method was used to investigate the ground states as well as the mechanical, electronic, magnetic and optical properties of M

Recently, 50-nm Heusler Mn3Al thin films were experimentally synthesized by Jamer et al. [Phys. Rev. Appl. (2017), 7, 064036] and the nominal zero moment, i.e. the fully compensated ferrimagnetic property, of these thin films was confirmed. That work motivated the current investigation on the martensitic transformation, electronic structure and magnetism of D03-ordered Mn3Al using first-principles calculations. Owing to tetragonal distortion, the martensitic transformation only occurs with tensile strain rather than with compressive strain and the half-metallic-type Mn3Al becomes a magnetic metal. Consequently, Mn3Al shows great potential for application as a ferromagnetic shape memory alloy. Moreover, not only did the martensitic transformation occur in Mn3Al, it was also observed in similar D03-ordered Mn3 Z (Z = B, Ga, Ge, Sb) compounds.

By using the full potential linearized augmented plane wave (FP-LAPW) method, the electronic properties of the layered BaAgChF (Ch = S, Se, Te) were investigated. Both the standard GGA and the TB-mBJ potential were used to model the exchange-correlation potential. To evaluate the spin-orbit coupling (SOC) effect, both the scalar relativistic and full relativistic calculations were performed. The SOC effect is found to be not negligible in the title compounds. The FP-LAPW band structure and the semi-classical Boltzmann transport theory were used to study the charge-carrier concentration and temperature dependences of the thermoelectric parameters, including Seebeck coefficient, electrical conductivity, thermal conductivity and figure of merit. Our results show that the values of the thermoelectric parameters of the p-type compounds are larger than that of the n-type ones. The optimal p-type doping concentrations and temperatures that yield the maximum values of the figure of merit of the title compounds were calculated. These are important parameters to guide experimental works.

The structural, electronic, optical and thermodynamic properties of the AlxIn1-xN (x = 0, 0.25, 0.50, 0.75 and 1) ternary alloys were investigated using the full potential linearized augmented plane wave (FP-LAPW) method in the framework of density functional theory (DFT). Optimized lattice parameter, bulk modulus and its pressure derivative were determined from suitable fit of the total energy versus volume with Murnaghan equation of state (EOS) for all considered alloys. Variations of the lattice parameter and bulk modulus with the Al concentration (x) deviate from Vegard’s law. Electronic band structure, dielectric function and refractive indices were investigated and computed for the considered alloys. It is found that the variations of the band gap, the static dielectric constant and static refractive index versus the Aluminum Al concentration obey to a quadratic polynomial. Temperature and pressure dependencies of the Gibbs free energy G, isochoric heat capacity CV, entropy S and Debye temperature θD were investigated via the Debye quasi-harmonic model for the Al0.5In0.5N ternary alloy. Furthermore, the elastic constants Cij, the bulk modulus B, Shear modulus G with Young modulus E and the Poison’s ratio v with the compressibility B/G were carried out in the cubic phase. Deduced results agree well with the available theoretical and experimental results.

First-principles density functional theory approach is adopted to determine the electronic, magnetic and structural characteristics of the Mn2CoAs1−xAlx (x = 0,0.25,0.50,0.75) Heusler alloys. The computations are carried out by WIEN2k code based on full-potential linearized augmented plane wave method (FP-LAPW). Moreover, the exchange-correlation energy functional is treated at the level of the generalized gradient approximation (GGA). Analysis of our computed results of the electronic band structure, as well as the density of states of the Mn2CoAs compound, show it a stable and half-metallic material with an energy band gap value of 0.48 eV. The calculated spin gap values are: 0.627 eV, 0.22 eV and 0.188 eV for Mn2CoAs0.75Al0.25, Mn2CoAs0.50Al0.50 and Mn2CoAs0.25Al0.75 respectively. Furthermore, the calculated total magnetic moment of the Mn2CoAs (4 µB) is found to be in agreement with the Slater–Pauling rule. Thus, our calculations show the Mn2CoAs1−xAlx (x = 0, 0.25, 0.50, 0.75) Heusler alloys potential materials for near future applications in spintronic because of their half-metallic ferromagnetism property.

A first-principles method has been employed to determine the electronic, magnetic and structural characteristics of the full-Heusler alloys Fe2VAl with Sn doping. All the calculations were performed by using a computational code based on full-potential linearized augmented plane wave method called WIEN2k. The electron exchange–correlation is treated by the generalized gradient approximation within a scheme developed by Perdew, Burke and Ernzerhof (PBE-GGA). The electronic band structures of Fe2VAl1−xSnx (x = 0, 0.25, 0.50, 0.75) compounds show that the majority-spin (spin-up) exhibits a metallic characteristic, whereas the minority-spin (spin-dn) have an energy band gap. Our calculations predict that Fe2VAl1−xSnx compounds are half-metallic ferromagnets with an integer value of magnetic moment, 0, 1, 2, and 3 μB, respectively. Our findings suggest that these materials are potential candidates for manufacturing spintronic devices.

In this study, first-principles investigations were performed using the full-potential linearized augmented plane-wave method of the structural and optoelectronic properties of thorium germinate (ThGeO4), a high-K dielectric material. Under ambient conditions, the structural properties calculated for ThGeO4 in the zircon phase were in excellent agreement with the available experimental data. Furthermore, using the modified Becke -Johnson correction method, the calculated band gaps and optical constants accurately described this compound. Finally, the thermal properties were predicted over a temperature range of 0–700 K and pressures up to 11 GPa using the quasi-harmonic Debye model, where the variations in the heat capacity, primitive cell volume, and thermal expansion coefficients were determined successfully.

Ab-initio calculations based on density functional theory have been performed to study the structural, electronic, thermodynamic and mechanical properties of intermetallic compounds Pt3Sc and Pt3Y using the full-potential linearized augmented plane wave(FP-LAPW) method. The total energy calculations performed for L12, D022 and D024 structures confirm the experimental phase stability. Using the generalized gradient approximation (GGA), the values of enthalpies formation are −1.23 eV/atom and −1.18 eV/atom for Pt3Sc and Pt3Y, respectively. The densities of states (DOS) spectra show the existence of a pseudo-gap at the Fermi level for both compounds which indicate the strong spd hybridization and directing covalent bonding. Furthermore, the density of states at the Fermi level N(EF), the electronic specific heat coefficient (γele) and the number of bonding electrons per atom are predicted in addition to the elastic constants (C11, C12 and C44). The shear modulus (GH), Young's modulus (E), Poisson's ratio (ν), anisotropy factor (A), ratio of B/GH and Cauchy pressure (C12–C44) are also estimated. These parameters show that the Pt3Sc and Pt3Y are ductile compounds. The thermodynamic properties were calculated using the quasi-harmonic Debye model to account for their lattice vibrations. In addition, the influence of the temperature and pressure was analyzed on the heat capacities (Cp and Cv), thermal expansion coefficient (α), Debye temperature (θD) and Gruneisen parameter (γ).

We report the results of studies on the structural, electronic and optical properties of MgSi1−xGexAs2(x = 0, 0.25, 0.5, 0.75 and 1) using density functional theory (DFT) based on the full-potential linear augmented plane wave (FP-LAPW) method. To treat the exchange-correlation potential for the total energy calculations, the generalized gradient approximation (WC-GGA) by Wu-Cohen was used. Additionally, the modified Becke Johnson (mBJ) potential approximation, which successfully corrects the band-gap problem, was used for the band structure calculations. The calculated lattice constants and band-gap values for these alloys are in good agreement with the available theoretical and experimental data. A decrease in the band gap is observed with an increasing Ge content. The dielectric function and absorption coefficient are calculated to investigate the optical properties. Electronic and optical properties reveal that these alloys should be very useful for applications in photonics, optoelectronics and optics.

A systematic ab initio investigation has been performed to determine the elastic stability, the structural and finite-temperature thermodynamic properties of copper iodide (CuI) in the zinc-blende phase under pressure. All calculations are carried out based on the pseudopotential density functional method, in which we employ the generalized gradient approximation of the revised Perdew-Burke-Ernzerhof form and local density approximation of Ceperly and Adler parameterized by Perdew and Zunger together with plane-wave basis sets for expanding the periodic electron density. The obtained normalized volume dependence of the pressure and the equation-of-state parameters including equilibrium volume, isothermal bulk modulus and its pressure derivatives are in excellent agreement with the experimental data and other theoretical results. The elastic constants are calculated and the investigation of the mechanical stability from the elastic constants under pressure indicates that the zinc-blende CuI is stable up to 10 GPa. Through the careful evaluation with the quasi-harmonic Debye model in which the phononic effects are considered, a complete set of thermodynamic data up to 800 K, including the bulk modulus, volume thermal expansion coefficient, heat capacity, entropy, Debye temperature, and Gruneisen parameter of CuI with zinc-blende structure is achieved. This set of data is considered as the useful information to understand the high-temperature and high-pressure properties of CuI.

First-principles calculations were performed to investigate the structural, elastic, electronic, optical and thermoelectric properties of the Zintl-phase Ae3AlAs3 (Ae = Sr, Ba) using two complementary approaches based on density functional theory. The pseudopotential plane-wave method was used to explore the structural and elastic properties whereas the full-potential linearised augmented plane wave approach was used to study the structural, electronic, optical and thermoelectric properties. The calculated structural parameters are in good consistency with the corresponding measured ones. The single-crystal and polycrystalline elastic constants and related properties were examined in details. The electronic properties, including energy band dispersions, density of states and charge-carrier effective masses, were computed using Tran-Blaha modified Becke-Johnson functional for the exchange-correlation potential. It is found that both studied compounds are direct band gap semiconductors. Frequency-de...