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In this paper, we report the results of first-principles calculations on the electronic structure of the superstoichiometric dihydrides TbH2.25 with space group symmetry I4/mmm. The calculations including structural relaxation are based on the DFT. The latter was implemented using the WIEN2k simulation code. The generalized gradient approximation (GGA) and local density approximation (LDA) were used for the exchange and correlation energy functionals. The structural and electronic properties of terbium superstoichiometric dihydrides with the tetragonal structure (I4/mmm) have been systematically investigated. The basic ground state properties (at 0 K) viz., lattice constants, bulk moduli and their pressure derivatives and total energies are calculated. The optimized unit-cell parameters under relaxation fit very well with the experimental findings. Obtained results on band structure and density of states show that the TbH2.25 (I4/mmm) system is metallic due to a non-vanishing density of states at the Fermi level.

Double perovskite oxide, Ba2YbTaO6 (BYT), has been studied under the realm of DFT-based calculation implemented in Wien2K code. Spin-polarized electronic and magnetic calculations show the 100% spin polarization across the Fermi level and confirm the half-metallic ferromagnetic (HMF) character for the compound. Bandgap (~ 3.47 eV) is calculated using the mBJ exchange correlation and found to be in good agreement with its reported experimental (3.95 eV) value. It has been found that Yb-f orbitals have major contribution in density of states (DOS) near and at Fermi levels. Optical spectra show that static refractive index is more than one (~ 4.5) and well correlated with the Penn Model. Both absorption and optical conductivity spectra show significance for its application in UV-based opto-electronic devices. Our studied electronic, optical, and magnetic properties suggest that material has significance in spintronic and optical devices.

The structural, electronic and thermodynamic properties of LaRuX (X = Si, Ge) compounds are investigated using density functional theory by the Wien2k code. Using the first-principles procedure, the Hubbard parameter of La 5d electrons and Ru 4d electrons of LaRuX (X = Si, Ge) compounds is calculated. In these calculations, the exchange–correlation potential is calculated using the generalized gradient approximation (GGA) and generalized gradient approximation plus Hubbard parameter (GGA + U). The calculated results indicate that LaRuX (X = Si, Ge) compounds are stable in the nonmagnetic phase. The electron density of states and band structure of LaRuX (X = Si, Ge) compounds within GGA and GGA + U approaches in the presence of spin orbit coupling are calculated. The obtained results of the electronic band structure show that LaRuX (X = Si, Ge) compounds have metallic behavior. Furthermore, thermodynamic properties of LaRuX (X = Si, Ge) compounds using the quasi-harmonic Debye model within GGA and GGA + U approaches are investigated.

Ab initio calculations have been performed by the linearized augmented plane wave (LAPW) method as implemented in the WIEN2K code within the density functional theory to obtain the structural, electronic and optical properties of ZnSnP2 in the body centered tetragonal (BCT) phase. The six elastic constants (C11, C12, C13, C33, C44 and C66) and mechanical parameters have been presented and compared with the available experimental data. The thermodynamic calculations within the quasi-harmonic approximation is used to give an accurate description of the pressure-temperature dependence of the thermal-expansion coefficient, bulk modulus, specific heat, Debye temperature, entropy Grüneisen parameters. Based on the semi-empirical relation, we have determined the hardness of the material; which attributed to different covalent bonding strengths. Further, ZnSnP2 solar cell devices have been modeled; device physics and performance parameters have analyzed for ZnTe and CdS buffer layers. Simulation results for ZnSnP2 thin layer solar cell show the maximum efficiency (22.9%) with ZnTe as the buffer layer. Most of the investigated parameters are reported for the first time.

In the framework of density functional theory, the first principle calculations are performed to investigate various physical properties of new series of half Heusler alloys KMnZ (Z = B, Si, Ge, As) by using WIEN2k code. The results of structural parameters show that ferromagnetic state is more stable, with Type 3, configuration than the non-magnetic and antiferromagnetic states for all KMnZ (Z = B, Si, Ge, As) compounds. All considered alloys KMnZ (Z = B, Si, Ge, As) are completely spin polarized and show half-metallic character because of the presence of band gap (BG) in minority-spin channels. The calculated magnetic moments are 3 µB, 4 µB, and 5 µB for KMnB, KMnSi (Ge), and KMnAs, respectively. The values of minority BG for KMnB, KMnSi, KMnGe, and KMnAs are 0.60 eV, 0.85 eV, 1.00 eV, and 1.20 eV, respectively. The origin of their HM gaps is also examined in addition to density of states and band structures. The Curie temperature (TC), within mean field approximation, is also calculated. The calculations for elastic constants and other mechanical parameters are computed to check the mechanical stability which revealed that all other alloys are stable with ductile nature except KMnB. From the results of several physical properties, it can be envisaged that these materials can be used for spintronic devices.

The structural and electronic properties of the Ni-doped SrTiO3 have been study by using the full-potential (Linearized augmented plane-wave method (FP-LAPW) within density functional theory (DFT). We employed the generalized gradient approximation (GGA) and modified Beck-Johnson (mBJ) GGA. The calculated band gaps are found to be decreased with the increase in In concentration. The mBJ-GGA band gaps are very close to experimental values as implemented in the WIEN2k simulation code. We studied the electronic properties of SrTiO3 and effect doping Ni on its. This study revealed that Ni doping of SrTiO3 had a significant impact on the structural and electronic properties of SrTiO3, and its structural stability can be improved by Ni doping SrTiO3. The band gap of SrTiO3 is 2.857 eV and 1.078 eV for SrNi0.125Ti0.875O3.

Since its discovery in 2004, graphene has attracted the intention of several researchers in the world because of its fascinating electronic and mechanical properties. Various theoretical and experimental works have been devoted to this material. In this paper, we used a full-potential linearized augmented plane-wave (FP-LAPW) method to investigate the structural, electronic, and mechanical properties of graphene in hexagonal structure within local density and generalized gradient approximations (LDA and GGA). Our results are found in good agreement with other theoretical and experimental contributions. Using a modified Becke–Johnsone GGA approximation, we have also confirmed that graphene is a zero-gap semiconductor with the presence of a Dirac cone. In our contribution, we have also calculated the elastic constants, the Young’s modulus and Poisson’s ratio of graphene that are found in good agreement with the results published in the literature.

This paper explores structural, phonon, electronic and thermoelectric properties of Zr0.25Ti0.75GeSb. By doping 0.25 Zr to TiGeSb the space group of this compound changes to P4/mm. Lattice constants and bulk modulus demonstrate relative increase compared to TiGeSb. This increment is low and expected. Furthermore, phonon calculations of Zr0.25Ti0.75GeSb were carried out by Quantum Espresso code. Electronic and thermoelectric calculations were performed using Wien2k software and accessory code Boltztrap. This compound has metallic nature and contribution of i orbitals among atoms with d orbital for atom “Ti1” is the highest. In thermoelectric properties, figure of merit of Zr0.25Ti0.75GeSb is significantly increased compared to bulk of TiGeSb in both xx and zz directions at low temperatures. However, at high temperatures it is lower.

The first-principle calculations were performed in the framework of the density functional theory (DFT) using FP-LAPW method as implemented in Wien2k code to determine the structural stability, electronic, and magnetic properties of quaternary Heusler alloys Cr2TaGe1-xSnx (x = 0, 0.25, 0.50, 0.75, 1.00), The results showed that for the compounds, the AlCu2Mnl-type structure is energetically more stable than CuHg2Ti-type structure at the equilibrium volume. The calculated lattice constants for Cr2TaGe and Cr2TaSn are 6.081 A and 6.311 A, respectively. For mechanical properties, shear modulus, Young’s modulus, elastic constants, Poisson’s ratio and shear anisotropy factor have studied. Their obtained values reveal that these compounds are mechanically stable. The electronic band structures and density of states of our compounds show a half metallic character with total magnetic moments, − 3.00 μB per formula unit with indirect band gap, 0.569 eV and 0.482 eV for Cr2TaGe and Cr2TaSn respectively. Regarding thermal properties such as the thermal expansion coefficient, heat capacity, and Debye temperature, we have applied a very suitable model for studying thermodynamics quantities called the quasi-harmonic Debye model. On the basis of these results, these alloys are predicted to be good candidates for future spintronic applications.

Structural, electronic and magnetic properties of the hexagonal magnetoelectric YMnO3 oxide in low symmetry were investigated using density functional theory calculations and the full-potential linearized augmented plane wave method implemented in the Wien2k code. The results showed that the internal atomic relaxation calculations are in good agreement with the experimental data. The obtained results from electronic band gap calculations using the Perdew–Burke–Ernzerhof generalized gradient approximation (GGA-PBE) reveal that the YMnO3 has a metallic character. However, the Tran–Blaha-modified Becke–Johnson (TB-mBJ) approach predicts a semiconductor type, as expected for YMnO3. The estimated band gaps are found to be close to 0.45 eV (ferromagnetic, FM) and 0.6 eV (anti-ferromagnetic, AFM). Moreover, calculations yielded a total magnetic moment of about 24 μB per unit cell. The magnetic moment carried by Mn atoms is revealed to be sensitive to the used approximation. Its value is equal to 3.3 μB and 3.5 μB for the GGA and GGA+mBJ approaches, respectively. Both values are in accordance with the experimental data.

The solar cells and thermoelectric generators are the main sources of renewable energy. In current article, we have analyzed the electronic, optical, and transport characteristics of K2TiI6 and Rb2TiI6 by density functional theory (DFT) based Wien2k code through modified Becke and Johnson (mBJ) potential. The structural and thermodynamic stability are certified by tolerance factor (0.99–1.0) and negative formation energy. The bonding nature is illustrated by color charge density. The band gap of 1.39 eV and 1.48 eV for K2TiI6 and Rb2TiI6 demonstrate the maximum absorption of light takes place in visible region (1.5 eV–3 eV), which makes them new potential materials for solar cells. Moreover, the reflection of light and optical loss is negligible in the visible region. The transport characteristics have been explained by classical Boltzman transport (CBT) based BoltzTraP code in terms of thermal to electrical conductivity ratio, Seebeck coefficient, and figure of merit. The figure of merit lies between 0.75 to 0.76, which is decent for thermoelectric characteristics.

The initial nucleation of gold clusters Aun (n = 1-5) on TiO2 rutile (110) reduced surface is studied using density functional theory and a full-potential augmented-plane-wave method implemented in the WIEN2k code. The first two gold atoms remained tied to the surface with a bond length similar to those belonging to other well-known related materials, while the other gold atoms do not spread over the surface; they preferred to form a new layer. The occurrence of relativistic effects produced a preferential triangle geometry for Au3 and a combination of triangular units for Au4 and Au5 . The Au-Au average distance increased from n = 2 to n = 5, indicating an expansion with a tendency to the bond distance found in the bulk. We are reporting an early 2D→3D transition of small folding, from Au3 →Au4 , followed by an Au4 →Au5 transition of evident 3D character.

In the present work, the structural, electronic, magnetic, elastic, thermodynamic, and thermoelectric properties of half-Heusler alloys RhFeX (with X = Ge, Sn) have been investigated using the full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) implemented in the WIEN2k code. The generalized gradient approximation of Perdew-Burke-Ernzerhof (GGA-PBE) and the Tran-Blaha-modified Becke-Johnson exchange potential method (TB-mBJ) has been used for modeling exchange correlation potential. The results obtained show that the two studied compounds are mechanically and dynamically stable. On the other hand, both compounds RhFeX (with X = Ge, Sn) exhibit a half-metallic ferromagnet behavior; their magnetic moments obey the Slater-Pauling rule with an absolute bias of 100% around the Fermi level. The thermodynamic properties including the isothermal bulk modulus, the heat capacity, the Debye temperature, and the thermal expansion coefficients of both compounds are investigated using the quasi-harmonic Debye model. According to the thermoelectric results, the values of the merit factor (ZT) are 0.935 and 0.952 at 300 K for RhFeGe and RhFeSn, respectively; these results indicate that our compounds are potentially good candidates for thermoelectric applications at low temperature.

We have studied the structural, electronic, magnetic, and elastic properties of full-Heusler alloys Co2YPb (Y = Ti, V, Fe, and Mo) with the help of ab initio calculation using Full Potential-Linearized Augmented Plane Wave (FP-LAPW) method which is based on density functional theory (DFT) implemented in the wien2k code with Generalized Gradient Approximation (GGA). For exchange and correlation potential, we have applied a modified version of the potential proposed by Becke—Johnson (mBJ) to our compounds in order to improve the band-gaps and approach them for experimental results. Electronic and magnetic properties show that the full-Heusler Co2YPb (Y = Ti, V, Fe, and Mo) are half-metallic ferromagnetic (HMF) compounds. Elastic properties indicate that Co2YPb is mechanically stable and each compound is ductile in nature.

Herein, we report the study of half-Heusler ScTiX (X = Si, Ge, Pb, In, As, and Tl) compounds for the first time employing the scheme of density functional theory (DFT). The influence of on-site Coulomb interactions is taken into account, and simulations are conducted in generalized gradient approximation with the added Hubbard U term (GGA + U). All the compounds were observed to have a narrow band gap on the spin-down configuration. Though spinning the majority channel (spin-up), it is found to be metallic. Consequently, all compounds are semi-metallic or half-metallic and 100% of spin polarized at the Fermi level. Various features, comprising structural, magnetic, elastic, and electronic properties, are calculated through full-potential linearized augmented plane wave (FP-LAPW) method, since they are incorporated in the computer simulation package of WIEN2k. Equilibrium lattice constants are observed for all the compounds which exist within the domain of 6.4–6.8 A°. The IRelast package is already integrated in WIEN2K that has been used for the elastic properties. Elastic features reflect the brittle character of all the material. The total magnetic moments for all such materials are greater than 3 μB, i.e., 3 μB of MTot. Therefore, the compounds show a strong ferromagnetic behavior. These are therefore expected to be used as shape base for thin layers within metastable situations for spintronic applications. The resulted elastic properties show that ScTiSi is ductile, while all other five compounds represent brittle nature. Above findings delight the prospect of ScTiX (X = Si, Ge, Pb, In, As and Ti) compounds in developing half-metallic HH compounds for spintronics and memory storage appliances.

The spinel oxides SnV2O4 and SnCr2O4 are analysed to reveal the mechanical, electronic and magnetic properties using Wien2k software. The negative formation energy and positive elastic constants sh...

The electronic structure, elastic, and magnetic properties of the Cr2NbSn1 − xPbx quaternary Heusler alloys have been investigated using the full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory and implemented in WIEN2k code. The exchange-correlation potential is evaluated using the generalized gradient approximation (GGA) within the Perdew–Burke–Ernzerhof (PBE) parameterization. Our results provide a theoretical study for the mixed Cr2NbSn1 − xPbx Heusler alloys in which no theoretical or experimental data are currently available. The AlCu2Mnl-type (L21) structure is more stable than the CuHg2Ti-type structure at equilibrium volume for the compounds. In their equilibrium L21 structure, all concentrations are magnetic and metallic. However, there is linear variation of the lattice parameter. The bulk modulus, the elastic constants, and the Debye temperature were studied with a variation of composition x of Pb. The mechanical results show that these compounds are mechanically stable. The quasi-harmonic Debye model, as implemented in the Gibbs code, was used to predict the thermal properties of the Cr2NbSn1 − xPbx alloys. These alloys seem to be a potential candidate of spintronic devices.

By using WIEN2k code, we investigated the mechanical and thermoelectric properties of magnesium based MgX2O4 (X = Rh and Bi) spinels. To compute the mechanical behavior of MgX2O4 (X = Rh and Bi), the Perdew-Bruke-Ernzerhof (PBEsol) flavor of generalized gradient approximation is used. From structural optimization, ground state lattice constant ( a 0 ) show a comparable with the previously evaluated theoretical and experimental values. The Born stability criterion represents that the investigated spinels are stable in the cubic phase and their ductile behaviors are observed by calculating Pugh’s ratio as well as Poisson ratio. Besides, thermodynamic behavior is concluded in terms of the Debye temperature. To investigate the electronic and thermoelectric behavior, the modified Becke and Johnson (mBJ) potential is employed. Finally, we investigated the thermoelectric behavior to represent the importance of studied spinels in thermoelectric appliances by calculating the figure of merit (ZT). High values of the See-beck coefficient and ZT at room temperature explores the potential of the studied spinels in thermoelectric devices.

Density functional theory calculations as employed in Wien2K code are used to investigate the structural, thermodynamic, and optoelectronic behavior of BeTiO3 perovskite at various pressures. The tolerance factor within the range of 0.93–1.04 suggests that the studied perovskite is thermodynamically stable in the cubic phase along with structural and mechanical properties. By inducing the pressure, the dependent specific heat capacity and the electron density are explored from 0 to 1000 K. At 132 GPA, the band gap becomes direct in nature (indirect band gap at 0 GPA), where the optical transitions take place.

The transition-metal dichalcogenides (TMDC) attracted a lot of attention for a variety of applications and more particularly as positive electrodes in lithium batteries. Among these materials the most intensively studied, we find semiconductors such as tungsten diselenide WSe2. In this work, we have perform first-principle calculations to investigate the structural and electronic properties of WSe2 compound, using the density functional theory DFT within the full-potential linearized augmented plane wave method (FP-LAPW) implemented in the code WIEN2k. The Generalized Gradient Approximation (GGA) as proposed by Perdew et al. was used to describe the exchange–correlation potential; and so to obtain the structural properties to assess the equilibrium lattice, the total energy of the system for different values of the primitive mesh and determining the volume at equilibrium, the compressibility modulus and the energy of the ground state, which are close to experimental results reported in the literature. The electronic properties were obtained by calculating the band structure and the density of state ″DOS″, by using three approaches: Local Density Approximation (LDA), Generalized Gradient Approximation (GGA) and modified Becke-Johnson (mBJ). The calculated energy bands indicate the semiconductor behavior of WSe2 with an indirect band gap of 0.9 eV using LDA, of 1 eV with GGA and 1.18 eV by mBJ. This last band gap value is the closest of the experimental result of 1.2 eV.

The zinc antimonide ZnSb is one of the most materials which have been studied intensively in recent years, due to its importance in thermoelectric applications, and as well as its use as an electrode in rechargeable Li-ion batteries. For this reason, we were interested in studying its structural and electronic properties. These properties have been calculated using the density functional theory DFT within the full potential linearized augmented plane wave (FP-LAPW) method used with WIEN2k code. The Generalized Gradient Approximation and the Local Density Approximations were used to model the exchange–correlation potential which was applied to determine the structural properties as well as the total energy (E0), the bulk modulus (B) and its first pressure derivative (B’), at a minimum equilibrium volume (V0). We also used the Tran-Blaha modified Beck Johnson (TB-mBJ) method to determine the total and partial density of states TDOS and PDOS respectively, which depicted that the electrons of Sb-5p orbital have a dominant contribution at the top of the valence band near the Fermi level, and show the sharp peaks in the conduction band. The electronic band structure shows clearly semiconductor behavior, with an indirect gap of 0.59 eV. This last result is in good agreement with an experimental result of 0.61 eV.

The structural and optoelectronic properties of AlxGa1−xN (x = 0, 0.125, 0.375, 0.625, 0.875, and 1) semiconductors are studied in detail by applying the full-potential linearized augmented plane-wave method in density functional theory in WIEN2k software. The lattice parameter, the bulk modulus, and its pressure derivative are calculated using the Perdew–Burke–Ernzerhof generalized gradient approximation and by fitting the calculated total energy to the Murnaghan equation. These parameters are found to be in excellent agreement with experimental and theoretical results for both the GaN and AlN compounds. For the Al0.125Ga0.875N, Al0.375Ga0.625N, Al0.625Ga0.375N, and Al0.875Ga0.125N alloys, because of the lack of the theoretical and experimental data, our results can be considered as first predictions. The Tran–Blaha modified Becke–Johnson approach (TB-mBJ) is applied to determine the optoelectronic properties. The results demonstrate that GaN and the AlxGa1−xN alloys with x = 0.125, 0.375, 0.625, and 0.875 have a direct Γ–Γ bandgap, whereas the binary AlN compound has an indirect Γ–X bandgap. Furthermore, the optical properties, such as the dielectric function, refractive index, reflectivity, absorption coefficient, and energy loss function, are presented and discussed in detail; their wide bandgap means that these compounds can be applied in optoelectronic devices for application in the main parts of the ultraviolet and visible spectrum.

Compositional variations in GaAs based ternary alloys have exhibited wide range alterations in electronic properties. In the present paper, first-principles study of GaAsxSb1 – x ternary alloys have been presented and discussed. Density functional theory (DFT) computation based on the full-potential (linearized) augmented plane-wave (FP-LAPW) method has been utilized to calculate the Density of States (DOS) and the band structure of ternary alloys GaAsxSb1 – x (x = 0, 0.25, 0.50, 0.75, 1). The calculations were performed using the exchange-correlation energy functional from Perdew, Burke, and Ernzerhof, a generalized-gradient approximation (GGAPBE) and Becke-Johnson exchange potential with local-density approximation (BJLDA) available within the framework of WIEN2k code. As compared to PBE, the results obtained from BJLDA are in close agreement with other experimental works. The DOS results show a reduction in bandgap as the Sb fraction is increased in GaAsxSb1 – x ternary alloys. The bandgap obtained by PBE and BJLDA are found to deviate from Vegard’s law, i.e., it doesn’t vary linearly with composition. However, the bandgap obtained by BJLD is found to closely match Vegard’s law when the bowing parameter is considered.

The first principle calculations on the structural, electronic structure as well as the magnetic properties of Ruddlesden-Popper Nd2MO4 (M = Sc and Y) compounds were accomplished by using the full-potential linearized augmented plane waves with local orbitals (FP-LAPW + lo) method within the spin-polarized density functional theory (spin-DFT) and implemented in the WIEN2k package. The exchange and correlation potential was treated with the generalized gradient approximation PBE-GGA for the structural properties. Moreover, the PBE-GGA + U approximation (where U is the Hubbard correlation term) is used to treat “d” and “f” electrons for the electronic and magnetic properties of these compounds. The equilibrium structural parameters such as: lattice constants (a0 and c0), bulk modulus (B0) and the first pressure-derivative of bulk modulus (B’), are optimized for all these alloys. The calculations of the electronic properties for the Ruddlesden-Popper Nd2MO4 (M = Sc and Y) compounds at their equilibrium lattice parameters disclose that the both compounds are half-metallic materials. The magnetic properties show that the total magnetic moment for the two Nd2ScO4 and Nd2YO4 compounds is found in integer value. The magnetic moment of Nd is reduced from its free space charge value of 4μB, whereas small magnetic moments are produced on the nonmagnetic O1 and O2 sites.

We used the density functional theory (DFT) based on full-potential linearized augmented plane wave (FP-LAPW) method implemented in WIEN2K code, to predict the structural, magnetic, electronic and elastic properties of the full-Heusler alloys Co2MB (M = V,Mn) and their MB-terminated (001) surfaces behavior. We showed that the studied alloys are more stable in the ferromagnetic order than the non-magnetic order. The calculated spin magnetic moments of Co2VB and Co2MnB were in good agreement with Slater-Pauling rule. The bulk of Co2VB was predicted to be a half-metallic ferromagnet with Eg = 0.63 eV, and the Fermi level lies in the middle of the indirect gap, and the electrons at EF were fully spin-polarized, unlike to Co2MnB which behaves as a metal. The half-metallicity of the bulk Co2VB was destroyed at (001) surface due to the symmetry reduction. The calculated elastic constants showed that compounds are stable and exhibit a ductile behaviour. The Young's modulus 3D representation showed that studied materials display a strong anisotropy.

Following the chronological stages of calculations imposed by the WIEN2K code, we have performed a series of density functional theory calculations, from which we were able to study the effect of strain on the kesterite structures for two quaternary semiconductor compounds Cu2ZnGeS4 and Cu2ZnGeSe4. Remarkable changes were found in the electronic and optical properties of these two materials during the application of biaxial strain. Indeed, the band gap energy of both materials decreases from the equilibrium state, and the applied strain is more pronounced. The main optical features are also related to the applied strain. Notably, we found that the energies of the peaks present in the dielectric function spectra are slightly shifted towards low energies with strain, leading to significant refraction and extinction index responses. The obtained results can be used to reinforce the candidature of Cu2ZnGeX4(X = S, Se) in the field of photovoltaic devices.

We have made systematic effort to investigate the structural, electronic, optical, and thermoelectric properties of Scandium–Gold-based HH compounds ScAuX (X = Si, Ge, Sn, Pb) using FP-LAPW method in the frame work of DFT and semi-classical Boltzmann equations using the constant relaxation time approximation as instigated in Wien2K code. The energy versus volume curves show that the explored compounds are observed to be stable in cubic non-magnetic phase. Electronic band structures as well as DOS plots predict that all explored compounds are indirect semiconductor in nature with TB-mBJ method, having energy gaps less than 0.5 eV, which gives a prediction for them to use as promising candidates for optoelectronic as well as solar cell devices. We can observe a very good optical response for these compounds because of its narrow band gap, predicting its application in photovoltaic applications. Transport properties results predict that these compounds can be used as good thermoelectric material as they have a high figure of merit value at room temperature and it increases with temperature upto 1200 K. The factor figure of merit (ZT) takes a maximum value of 0.82, 0.72, 0.69 and 0.80 at T = 1200 K for ScAuX (X = Si, Ge, Sn, Pb). We have used ideal p-type or n-type levels to attain optimum ZT from the computed power factor as a function of carrier concentration and chemical potential, and this will provide experimentalists with guidance to find suitable compositions to synthesize thermoelectric materials with higher performance.

In this study, structural, electronic, magnetic, elastic and thermal properties of Co-based Quaternary Heusler alloys (QHAs) CoYTiZ ([Formula: see text], Ga, Si, Ge) have been investigated by Wien2k code. The calculations have been performed using full-potential linearized augmented plane wave (FP-LAPW) method. Generalized Gradient Approximation (GGA) method has been adopted. Structural properties have been explored for three different Wyckoff positions. From the geometry optimization calculations, it is concluded that all these alloys are stable in Type-III crystal structure. Moreover, magnetic phase optimization revealed ferro-magnetic (FM) phase as stable one. Results of electronic properties have shown metallic character for CoYTiAl, CoYTiGa, CoYTiGe while nearly half metal (HM) character for CoYTiSi. Magnetic moment obeys Slater Pauling rule (SP) for these alloys. To check out the mechanical stability, elastic properties have been investigated. Elastic parameters have shown the ductile nature of these alloys. The values for melting temperature ([Formula: see text] have confirmed the thermal stability of the studied alloys.

The first-principles calculations of Co(Mo,Tc)MnSb compounds were performed by using Wien2k with Generalized Gradient Approximation (GGA) and Tran Blaha modified Becke Johnson (TB_mBJ) methods. All compounds were obtained as ferromagnetic (FM) materials according to volume-energy optimization curves. In GGA method, both compounds have metallic ferromagnet nature while these were in TB_mBJ method nearly half-metallic ferromagnet characters. In spin-down band structures, both compounds had indirect band gaps in both methods used. The total magnetic moment values were completely compatible with the Slater-Pauling (SP) rule and these values were obtained as 3.00 and 4.00 μ B /f.u. for Co(Mo,Tc)MnSb compounds, respectively. According to elastic calculations, Co(Mo,Tc)MnSb compounds are elastically stable and ductile materials . The Debye temperatures of Co(Mo,Tc)MnSb compounds were obtained above the room temperature as 408.040 K and 444.079 K, respectively.

A detailed investigation of the electronic structure in the neighborhood of Cd impurities in ${\mathrm{CeO}}_{2}$ has been performed by ab initio calculations to elucidate the interplay between the oxygen vacancies and electric quadrupole interactions. The quadrupole frequency related to the major component of the electric-field gradient (EFG) at impurities sites from its neighboring charge density as well as its symmetry were calculated by simulating oxygen vacancies at oxygen nearest neighbor of Cd. Results show a very good agreement with experimental hyperfine interactions measurements at the $^{111}\mathrm{Cd}$ nucleus replacing Ce at ${\mathrm{CeO}}_{2}$. A systematic mapping of oxygen vacancies in ${\mathrm{CeO}}_{2}$ supercells was proposed within the framework of density-functional theory using the wien2k code focusing on the electronic distribution in the vicinity of Cd impurities. Results show that the calculated values of EFG crucially depend on impurity-vacancy complex position and the striking axial symmetry observed when an oxygen monovancy is at the nearest neighborhood of Cd is explained by a rearrangement of its $p$ orbitals.

We propose a hybrid approach which employs the dynamical mean-field theory (DMFT) self-energy for the correlated, typically rather localized orbitals and a conventional density functional theory (DFT) exchange-correlation potential for the less correlated, less localized orbitals. We implement this self-energy (plus charge density) self-consistent DFT+DMFT scheme in a basis of maximally localized Wannier orbitals using Wien2K, wien2wannier, and the DMFT impurity solver w2dynamics. As a testbed material we apply the method to SrVO$_3$ and report a significant improvement as compared to previous $d$+$p$ calculations. In particular the position of the oxygen $p$ bands is reproduced correctly, which has been a persistent hassle with unwelcome consequences for the $d$-$p$ hybridization and correlation strength. Taking the (linearized) DMFT self-energy also in the Kohn-Sham equation renders the so-called "double-counting" problem obsolete., Comment: 2nd version as submitted, taking into account the k-dependence of the double counting on the DMFT side. 10 pages, 4 figures

A series of strontium calcium tungstates Sr1-xCaxWO4 powders with (x = 0; 0.25; 0.5; 0.75 and 1.0) were prepared by solid-state reaction method and analyzed by X-ray diffraction (XRD). All these compositions possess a tetragonal scheelite structure with I41/a space group. Raman active vibrational modes in the range from 20 to 1000 cm-1 of the series Sr1-xCaxWO4 with tetragonal structure exhibit 13 modes in arrangement with the Group theory analysis of structural Raman-active modes. The optical properties were investigated using the diffuse reflectance UV–visible absorbance spectrum. Based on Density Functional Theory (DFT) and using full Potential-linearized Augmented Plane Wave (FP-LAPW) method with the Local Density Approximation and the Generalized Gradient Approximation (GGA), implemented in the Wien2k package, we have investigated electronic and optical properties of all the compositions. The results indicate a decrease in the values of the optical direct bandgap (from 4.29 to 3.87 eV) with the increase of Ca into SrWO4 lattice, which is in good agreement with our experimental results.

Structural, elastic, electronic and magnetic properties of the quaternary Heusler alloys are calculated using the full-potential linearized augmented plane wave (FP-LAPW) method in the framework of the density functional theory (DFT) and implemented in WIEN2k code. The exchange-correlation potential is evaluated using the generalized gradient approximation (GGA) within the Perdew-Burke-Ernzerhof (PBE) parameterization. Our theoretically results provide predictions for the mixed in which no experimental and theoretical data are currently available. The lattice parameter and bulk modulus as well the elastic constants and their related elastic moduli for have been calculated. Also, the electronic properties including density of states and band structures indicate the metallic character for . Morever, this quaternary Heusler alloy is found to be ferromagnetic, ductile and anisotropic in nature.