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Context: In this study, the structural, elastic, electronic, and optical properties of Cs2GeBeBr6 and Cs2SnBeBr6 halide double perovskites (HDPs) were investigated using density functional theory (DFT) calculations. Notably, the Tran-Blaha modified Becke-Johnson (TB-mBJ) method was employed to predict indirect band gaps of 2.434 eV for Cs2GeBeBr6 and 2.855 eV for Cs2SnBeBr6. The stability of these compounds in a cubic (Fm-3m) structure was confirmed through formation energy, cohesive energy, tolerance factor, and elastic constants. Furthermore, the ductile nature of the materials was demonstrated through Poisson's and Pugh's ratios. Our optical property analysis, spanning the 0–13 eV energy range, revealed key insights into the dielectric functions, extinction coefficient, electron energy loss, refractive index, optical conductivity, reflectivity, and absorption coefficient. These results highlight the potential of Cs2GeBeBr6 and Cs2SnBeBr6 for future optoelectronic and photovoltaic applications. Methods: In this investigation, we employed density functional theory (DFT), implemented using the Wien2k package. The exchange and correlation potentials were treated using the generalized gradient approximation (GGA) and the Tran-Blaha modified Becke-Johnson (TB-mBJ) method. To evaluate dynamic stability, we analyzed the phonon band structures using the CASTEP code. [ABSTRACT FROM AUTHOR]

This study utilizes density functional theory (DFT) with the Tran–Blaha modified Becke–Johnson (TB-mBJ) exchange potential in the WIEN2k framework to comprehensively investigate the structural, electronic, elastic, and optical properties of Rb2TlIrF6 and Rb2TlRhF6 double perovskite compounds. Structural stability assessments affirm that both materials maintain their integrity under standard conditions, demonstrating robust frameworks. The calculated elastic constants reveal mechanical stability, elasticity, and directional anisotropy, emphasizing their resilience and adaptability in varied environments. Electronic band structure calculations categorize Rb2TlIrF6 and Rb2TlRhF6 as direct bandgap semiconductors, with respective bandgaps of 2.61 eV and 1.94 eV at the L–L symmetry points, underscoring their potential in optoelectronic applications. The optical properties were analyzed through key parameters: refractive index n(ω), optical conductivity σ(ω), reflectivity R(ω), absorption coefficient α(ω), and extinction coefficient k(ω). Additionally, the real and imaginary parts of the dielectric function ∊1(ω) and ∊2(ω) were evaluated, indicating effective light interaction and absorption properties in the visible to UV range. These findings suggest that Rb2TlIrF6 and Rb2TlRhF6 exhibit advantageous optoelectronic characteristics suitable for semiconductor and next-generation electronic devices.

The zinc-based perovskites ZnLiX3 (X = Cl or F) were investigated for their structural, electronic, and optical properties using the WIEN2k package within density functional theory (DFT). Structural properties were calculated using the generalized gradient approximation (GGA), while the modified Becke-Johnson (mBJ) potential was applied for a more accurate description of the optical and electronic properties. Both compounds are confirmed to be stable, crystallizing in the cubic Pm-3 m (No. 221) space group. ZnLiCl3 has an indirect band gap of 0.30 eV between the Γ and M symmetry points, indicating semiconducting behaviour, while ZnLiF3 exhibits an indirect band gap of 5.45 eV, typical of an insulating material. The electronic states contributing to the band structure were analyzed using the total density of states (TDOS) and partial density of states (PDOS). Optical properties, evaluated in the energy range of 0–14 eV, reveal strong optical conductivity and absorption at higher energies, while both materials show transparency to lower-energy photons. These findings suggest that ZnLiCl3 and ZnLiF3 are suitable candidates for high-frequency UV optoelectronic device applications.

To explore a good candidate for solar cell applications as an alternative to lead-independent materials, we calculated the structural and mechanical stability of the Rb2TlSbX6 (X = Cl, Br, I) compounds with PBEsol potential. The optoelectronic and thermoelectric behaviors of these compounds are computed with TB-mBJ potential. Our results indicate that these materials possessed excellent structural, mechanical, and thermal stability on the basic values of their Goldsmith’s, elastic parameters and negative formation energies. The dynamic stability is observed through phonon dispersion curve and found that all materials are dynamically stable. The computed values of Poisson and Pugh ratios and a positive value of Cauchy’s pressure indicate the ductile nature of these materials. We observed the low direct bandgaps for Rb2TlSbCl6, (1.486 eV), Rb2TlSbBr6 (2.07 eV), and Rb2TlSbI6 (1.04 eV) unlike the majority of halide double perovskite family have large bandgap values in literature. In addition, the computed optical and thermoelectric characteristics of the Rb2TlSbX6 (X = Cl, Br, I) materials show large values of absorption and optical conductivity with low reflectivity and energy loss at small energy ranges. According to these findings, all these halogen-based double perovskite materials have the potential to be employed as photovoltaic absorb materials in solar cell applications. Furthermore, the large values of the Seebeck coefficient, high-power factor and figure of merit (ZT) at room temperature also ensured their significance for thermoelectric generators.

Double perovskites have garnered significant attention for use in renewable energy applications, particularly solar cells. The development of organic-inorganic hybrid halide perovskite solar cells has advanced rapidly over the last ten years. In this article, fundamental aspects of transport properties of Cs2AgGaCl6 have been illustrated using DFT-based simulation. Constantly is covered that the calculated lattice constant agreed with the available experimental data. With an indirect band gap, the electronic profile demonstrates a semiconducting nature. Reporting bandgap of 1.20 eV for Cs2AgGaCl6. This bandgap remains suitable for solar cell semiconductors. The computed values of effective masses reveal that effective masses of holes are greater than those of electrons. Further various optical parameters have also been examined. The absorption of light in the visible and ultraviolet spectrums is guaranteed by the absorption bands 2.7–4.2 eV and 3.5–4.5 eV. We believe that such insights offer a new starting point and a framework for future research. So, knowledge and drive gained from these studies will stimulate more theoretical investigation into novel perovskite-based materials with novel applications.

Context and results: The study examines the physical characteristics of Co2ZrZ compounds using the Wien2k code and the Anisimov and Gunnarsson approach. Results show metallic attributes in Co2ZrBi and Co2ZrAs, while Co2ZrPb exhibits semi-metallic tendencies. Energy gap evaluations reveal significant infrared transitions, indicating altered electron mobility compensated by increased ultraviolet absorption. These compounds have potential in space solar energy applications due to UV light absorption capabilities, especially in Co2ZrPb. The study also identifies optical phenomena like “super-luminescence” and plasmatic oscillations. Computational and theoretical techniques: The study uses computational techniques like Wien2k calculation code and Hubbard parameter calculations to investigate Co2ZrPb, a compound with potential for space energy applications. Energy gap assessments are conducted using GGA and mBJ-GGA methods. The study also analyzes the optical behavior of the compounds, including infrared and ultraviolet absorption. The BoltzTraP code is used for thermoelectric investigations, revealing a P-type charge carrier predominance in Co2ZrPb. This comprehensive approach provides valuable insights into electrical conductivity and thermoelectric properties. [ABSTRACT FROM AUTHOR]

Context: We comparatively investigate the properties of pure ZnO and 2 at. % Al doping concentration of ZnO, AZO, as potential candidates for specific applications. Methods: Calculations were carried out, using Wien2k package, to deduce structural, electronic, optical thermoelectric, and properties of both ZnO and AZO materials via the combination of GGA and mBJ approximations. Results: It is shown that Al doping of ZnO (AZO) improves its optical properties; the deduced direct fundamental gap is enhanced due to the Burstein–Moss effect. Moreover, the dielectric function, at lower energies, confirms the existence of an extra strong fluctuation in the dispersive real part ɛ1(ω) and a high peak for absorptive imaginary parts ɛ2(ω) which are due to a variation in specific molecular bonding and the transition between the occupied and the non-occupied states. The critical point, observed at 2.81 eV for pure ZnO, is shifted to 3.3 eV in 2 at. % AZO, confirming a larger optical band gap. The reflectivity values slightly decreased for 2% AZO. The investigation of thermoelectric parameters as a function of chemical potential at different temperatures ranging from 300 to 900°C showed that these structures can be considered for good thermoelectric devices with (i) high absolute values of Seebeck coefficient: ׀SZnO׀ = 1.16 mV/K and ׀SAZO׀ = 0.746 mV/K, (ii) no effect of temperature on electrical conductivity but a strong effect on thermal conductivity, (iii) a high value approaching unity for the figure of merit. Hence, these properties and their improvements, introduced by Al doping of ZnO, lead specific and more uses in optoelectronics, energy, and piezoelectric applications. [ABSTRACT FROM AUTHOR]

Perovskite solar cells are the future of energy production due to the high- efficiency and low production costs. In this work, the structural, electronic and optical properties of the tetragonal inorganic halideperovskiteRbSeBr3 are performed using the full potential linearized augmented plane waves (FP-LAPW) method with the PerdewBurke–Ernzerh generalized gradient approximation (PBE-GGA) as well as the local density approximation (LDA) and the modified Becke-Johnson (mBJ-LDA) as exchange correlation potentials using Wien2k code. Furthermore, the thermoelectric propertieshave been calculated using BoltzTrap code, the obtained results show that the studied compound (RbSeBr3) has a metallic character and can be used as an absorber in UV-interval; on the other hand the thermoelectric power reveals a high value.

Thermoelectric materials have widely used applications in technological areas such as electronic devices and data storage. TlInSe2 and TlInTe2 compounds are among these thermoelectric materials. In this study, while the structural, electronic, and optical properties of TlInSe2, TlInTe2, Tl0.75Na0.25InSe2 and Tl0.75Na0.25InTe2 compounds have been examined with the WIEN2k program based on DFT, their thermoelectric properties have been calculated with another program BoltzTrap. The electronic calculations show that, all compounds exhibit indirect band gap properties. In addition, the band gap energy of Tl0.75Na0.25InSe2 is shifted in the electromagnetic spectrum. The optical properties are found to change depending on the direction for all compounds. Finally, the thermoelectric parameters have been calculated depending on temperature. It is thought that especially the results for Na-doped compounds will be a leading reference for experimental studies.

This study is aimed at exploring the electronic, magnetic, and magneto-optical properties of double perovskites Ca2FeIrO6 and Ca2CoIrO6 with monoclinic structure (space group P21/𝑐) in order to examine their potential applications in spintronic and photovoltaic devices. The calculations were done using the full-potential linearized augmented plane wave within the density functional theory. For the electronic exchange-correlation function, we used the generalized gradient approximation (GGA) and GGA+U (Hubbard potential), and spinorbit coupling (SOC). The study showed that Ca2FeIrO6 and Ca2CoIrO6 exhibit a monoclinic structure (space group P21/𝑐). The structure relaxation shows an antiferromagnetic behavior in both systems with a magnetic moment of about 6.00𝜇𝐵 for Ca2FeIrO6 and 4.00𝜇𝐵 for Ca2CoIrO6 by using GGA+U approximation. The results of GGA and GGA+U predict the half-metallic behavior of Ca2FeIrO6 and Ca2CoIrO6. The magneto-optical polar Kerr effect (MOKE) was examined by studying the variation of Kerr and ellipticity rotation. The Kerr rotation angle is 1.3◦ at 4.82 eV and -1.21◦ at 4.3 eV, and the ellipticity angle is -1.21◦ at 4.3 eV for Ca2FeIrO6. In the case of Ca2CoIrO6, the Kerr rotation angle is -1.04◦ at 4.05 eV; the significant Kerr rotation in both compounds may suggest the application of these materials in optoelectronics bias. The named compounds have a potential application in the field of spintronics and its devices, such as in optoelectronics technologies. [ABSTRACT FROM AUTHOR]

The purpose of this study is to conduct theoretical investigations on the electronic, structural and magnetic properties of lithium niobate (LiNbO3) doped with different concentrations of the transition metal chromium (Cr). All properties of LiNb1−xCrxO3 compounds (x = 0.25, 0.50 and 0.75) are achieved with spin-polarized density functional theory by the GGA-PBE and the TB-mBJ approximations. To ensure the stability of the LiNb1−xCrxO3 quaternary alloy in the ferromagnetic state, the total energy released from the optimized structure and the defect formation energy were calculated. The classical Heisenberg model estimated the Curie temperature of the compounds. The material studied exhibits a 100% spin-polarized semi-metallic ferromagnetism behaviour. In all compounds, the data of the magnetic moment demonstrated that the chromium impurity atom is the most important source by comparison with the Nb and Li, which have minor contributions. In addition, the magnetic moment of the Cr atoms decreases with doping; this comes from the p–d hybridization between the Cr-3d and O-2p states. The half-metal gap (GHM), the most important factor in spintronics applications, was also calculated. In addition, to assess the effects of the exchange separation process, the crystal field separation energy, the exchange separation parameters, and the exchange constants N0α, N0β, and ΔEC, ΔEV are predicted. [ABSTRACT FROM AUTHOR]

Renewable energy prices are decreasing, making it easier to make energy systems that are good for the environment. High-density storage for renewable energy is possible with hydrogen. This work focuses on the theoretical study of LiXH3 (where X = Ti, Mn, and Cu), including their structural, electronic, mechanical, thermoelectric, and hydrogen storage properties, using first-principles calculations. LiCuH3 is more stable than LiMnH3 and LiTiH3, based on the optimization graph. The electronic properties show the metallic nature of these studied hydrides. Born's criterion indicates that all studied hydrides are brittle for various mechanical applications. LiTiH3, LiMnH3, and LiCuH3 are all thought to be able to store hydrogen with gravimetric storage capacities of 5.22%, 4.66%, and 4.11%, respectively. Based on how their thermoelectric properties change with temperature, all the materials under study can absorb heat energy, which shows that they are both electrically and thermally conductive. [ABSTRACT FROM AUTHOR]

In this study, the investigations of structural, electronic, optical, and magnetic properties of a scintillating double perovskite halide (Cs2LiCeCl6) by using the full-potential linearized augmented plane wave (FP-LAPW) method in the framework of density functional theory (DFT) is reported. The optimized lattice constant (a0) is fully consistent with the experimental results, and the ground state optimized energy confirms the cubic (Fm 3¯ m space group) stability of the compound. The electronic band structures and densities of states are analyzed within approximations of PBE-GGA and TB-mBJ to have precise and accurate results. In the spin-up channel the metallic behavior of the compound is confirmed, while in the spin-down channel there is a band gap of 3.83 eV with an indirect nature from Γ-X, so clarifying its behavior towards semiconductors and thus overall making the compound to be half-metallic, and hence, it is clear that the material exhibit spin polarization. The ferromagnetic behavior is verified by the asymmetric density of states in both spin channels and the optimized energy volume curve in spin-polarized calculations. The optical parameters are computed and it is found that the compound Cs2LiCeCl6 possesses high optical conductivity, absorption coefficient and compared in both approximations and analyzed in the energy range of (0–20) eV and hence predict the applications of this material in high-frequency ultraviolet devices and also for particle detection.

Herein the first-principle modeling within the DFT framework is used to investigate the structural, optoelectronic, elastic, and thermoelectric properties of BaMF3 (M = Ag and Cu) ternary halide Perovskites compounds. The computed tolerance factors for BaAgF3 and BaCuF3 are 0.919 and 0.991 respectively, indicating that the cubic crystal phase of these selected compounds is thermodynamically and mechanically stable. It is found that both the compounds are structurally stable according to the Birch-Murnaghan fit curve for optimization. The IRelast package is used for investigating the elastic properties of both cubic compounds and the findings show that these compounds are mechanically stable, scratch-resistant, ductile, anisotropic, and resistant to plastic deformation. The Trans-Blaha modified Becke-Johnson (TB-mBJ) approximation is employed to determine electronic properties with accuracy and precision. The electronic-band structure analysis depicts a narrow band gap semiconductor nature of BaAgF3 and BaCuF3 compounds which displays indirect band gaps of 0.2 eV for BaAgF3 and 0.3 eV for BaCuF3 at the high symmetrical points from (Γ–M). Furthermore, the computations of total densities of states (TDOS) and partial densities of states (PDOS) are carried out to determine how different states contribute to the various band structures. The optical characteristics of BaAgF3 and BaCuF3 are comprehensively examined in 0–40 eV energy ranges. The selected materials possess high optical conduction and absorption coefficients at the high level of photon energies and show transparency at low incident photon energy ranges. The investigations of optical properties led us to the conclusion that BaAgF3 and BaCuF3 are suitable to use in high-frequency UV devices. The thermoelectric properties show that both materials hold high-power factors, electrical conductivity, and figures of merit (ZT), indicating that they are good thermoelectric materials. This is the first theoretical computational systematic analysis of structural, optoelectronic, elastic, and thermoelectric properties of BaMF3 (M = Ag and Cu) that will be experimentally validated to our knowledge.

Thermoelectric materials have widely used applications in technological areas such as electronic devices and data storage. TlInSe2 and TlInTe2 compounds are among these thermoelectric materials. In this study, while the structural, electronic, and optical properties of TlInSe2, TlInTe2, Tl0.75Na0.25InSe2 and Tl0.75Na0.25InTe2 compounds have been examined with the WIEN2k program based on DFT, their thermoelectric properties have been calculated with another program BoltzTrap. The electronic calculations show that, all compounds exhibit indirect band gap properties. In addition, the band gap energy of Tl0.75Na0.25InSe2 is shifted in the electromagnetic spectrum. The optical properties are found to change depending on the direction for all compounds. Finally, the thermoelectric parameters have been calculated depending on temperature. It is thought that especially the results for Na-doped compounds will be a leading reference for experimental studies. [ABSTRACT FROM AUTHOR]

Structural, electronic, optical and elastic properties of Silver based Perovskite AgXCl3 (X = Ca, Sr) are studied by utilizing wien2k package with in DFT. The structural investigation reveals their stability and shows that these compounds are cubic with space group pm-3m 221. For electronic properties the band structure and density of states are computed which indicates the semiconducting nature of both compounds. Elastic constants, Pugh’s ratio, bulk modulus, Poisson’s ratio and anisotropy factor are studied for the analysis of elastic characteristic. The Pugh’s ratio describes the ductile nature of the compounds and ionic nature is determined from the evaluated Cauchy pressure. Optical parameters such as dielectric function, extinction coefficient, refractive index, absorption coefficient, reflectivity and optical conductivity are calculated in the energy range of 0 eV–35 eV. The thermal stability is conformed from the thermal property. The study of these compounds reveals that they can be potential candidates for optoelectronic devices.

• Structural Stability: ZnLiCl 3 and ZnLiF 3 crystallize in the cubic Pm-3 m (No. 221) space group, confirmed to be stable via DFT calculations using the WIEN2k package. • Band Gap Analysis: ZnLiCl 3 has an indirect band gap of 0.30 eV (semiconducting), while ZnLiF 3 has an indirect band gap of 5.45 eV (insulating), based on electronic band structure calculations. • Electronic Structure: The total and partial density of states (TDOS and PDOS) were analyzed, identifying the electronic states contributing to the band structure for both compounds. • Optical Properties: Both materials exhibit strong optical conductivity and absorption in the higher energy range (0–14 eV) and transparency to lower-energy photons, making them highly suitable for UV applications. • Application Potential: The study suggests ZnLiCl 3 and ZnLiF 3 as promising candidates for high-frequency UV optoelectronic devices due to their optical and electronic characteristics. The zinc-based perovskites ZnLiX 3 (X = Cl or F) were investigated for their structural, electronic, and optical properties using the WIEN2k package within density functional theory (DFT). Structural properties were calculated using the generalized gradient approximation (GGA), while the modified Becke-Johnson (mBJ) potential was applied for a more accurate description of the optical and electronic properties. Both compounds are confirmed to be stable, crystallizing in the cubic Pm-3 m (No. 221) space group. ZnLiCl 3 has an indirect band gap of 0.30 eV between the Γ and M symmetry points, indicating semiconducting behaviour, while ZnLiF 3 exhibits an indirect band gap of 5.45 eV, typical of an insulating material. The electronic states contributing to the band structure were analyzed using the total density of states (TDOS) and partial density of states (PDOS). Optical properties, evaluated in the energy range of 0–14 eV, reveal strong optical conductivity and absorption at higher energies, while both materials show transparency to lower-energy photons. These findings suggest that ZnLiCl 3 and ZnLiF 3 are suitable candidates for high-frequency UV optoelectronic device applications. [ABSTRACT FROM AUTHOR]

This study is aimed at exploring the electronic, magnetic, and magneto-optical properties of double perovskites Ca_2FeIrO_6 and Ca_2CoIrO_6 with monoclinic structure (space group P21/c) in order to examine their potential applications in spintronic and photovoltaic devices. The calculations were done using the full-potential linearized augmented plane wave within the density functional theory. For the electronic exchange-correlation function, we used the generalized gradient approximation (GGA) and GGA+U (Hubbard potential), and spin-orbit coupling (SOC). The study showed that Ca_2FeIrO_6 and Ca_2CoIrO_6 exhibit a monoclinic structure (space group P21/c). The structure relaxation shows an antiferromagnetic behavior in both systems with a magnetic moment of about 6.00 μB for Ca_2FeIrO_6 and 4.00 μB for Ca_2CoIrO_6 by using GGA+U approximation. The results of GGA and GGA+U predict the half-metallic behavior of Ca_2FeIrO_6 and Ca_2CoIrO_6. The magneto-optical polar Kerr effect (MOKE) was examined by studying the variation of Kerr and ellipticity rotation. The Kerr rotation angle is 1.3º at 4.82 eV and -1.21º at 4.3 eV, and the ellipticity angle is -1.21º at 4.3 eV for Ca_2FeIrO_6. In the case of Ca_2CoIrO_6, the Kerr rotation angle is -1.04º at 4.05 eV; the significant Kerr rotation in both compounds may suggest the application of these materials in optoelectronics bias. The named compounds have a potential application in the field of spintronics and its devices, such as in optoelectronics technologies.

Prediction of new materials is crucial for the advancement of technology. Here, in this research work, the first-principle computation has been conducted utilizing the WIEN2K package to probe the structural, electronic, mechanical, and optical properties of barium-based chloroperovskites BaMCl3 (M = Ag, Cu) compounds. The optimized lattice constants are calculated for both compounds which are 9.90 Bohr for BaAgCl3 and 9.38 Bohr for BaCuCl3. To obtain better and more precise results for the electronic band's structure, TDOS and PDOS (total and partial density of states), and the TB-mBJ potential approximation are employed. The indirect band gap (R–Γ) is found for both compounds having values of 1.173 eV and 2.30 eV for BaCuCl3 and BaAgCl3, respectively, which depicts its semiconducting nature. The calculation of elastic properties is conducted with IRelast code. The Cauchy pressure, Bulk modulus, Young's modulus, Shear modulus, anisotropic ratio, Kleinman parameters, and Poisson's ratio are calculated from the obtained elastic constants. The computation of elastic parameters indicates that the interested chloroperovskites are anisotropic, mechanically stable, hard to scratch, and ductile. From 0 eV to 40 eV incident photon energy ranges, the various optical parameter such as refractive index, absorption coefficient, dielectric function, reflectivity, extinction coefficient, and optical conductivity are analyzed. These compounds absorb maximum light within 5 to 25 eV incident photon energy. Hence, these materials are good light absorbers, therefore, they can be used in optoelectronic devices for high-frequency applications. [ABSTRACT FROM AUTHOR]

Inverse perovskites are the counterparts to the largest family of crystalline perovskite materials and have attracted significant research interest because of their unconventional physical and chemical properties. Perovskite materials have been studied widely; however, less attention has been paid to their counterparts (inverse perovskites). In the present study, we report on the structural, electronic, elastic, mechanical, magnetic and thermodynamic properties of unexplored Rh-based XCRh3 (X = Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Zr, Nb, Mo, Tc, Ru, Pd, Ag) inverse perovskites. The first-principles density functional theory-based linearized augmented plane wave method as implemented in the Wien2k package with the generalized gradient approximation was employed for the investigation of the physical properties. The computed formation energies showed that the majority of these materials comparatively favor the ferromagnetic phase over the non-magnetic phase. Amongst the studied XCRh3, X = Ti-, V-, Cr-, Mn-, Zn- and Zr-based materials comprise negative formation energies confirming the energetic stability. All the compounds other than NbCRh3 and MoCRh3 were found mechanically stable. Spin-projected electronic properties of XCRh3 revealed the conducting features in both spin versions. The large magnetic moments per unit cell (> 3μB) of CrCRh3, MnCRh3, FeCRh3 and TcCRh3 were observed with dominant contribution from X-atoms. Mechanical anisotropy and other bulk mechanical parameters are elaborated and discussed in detail. The thermodynamic properties including specific heat capacity, thermal expansion coefficient and Debye temperature are scrutinized at different temperature and pressure ranges. [ABSTRACT FROM AUTHOR]

First-principles total energy calculations were performed to study the stability of Rh2TMSn (TM=Cr, Mn and Fe) toward different magnetic ordering, ferromagnetic (FM), antiferromagnetic type I (AFM-I) and antiferromagnetic type II (AFM-II). We studied the effects of electron correlation on the magnetic stability of the compounds in both cubic and tetragonal structures using density functional theory (DFT) within the generalized gradient approximation (GGA) and GGA+U. The results show that the electron correlation has an important role in determining the magnetic stability of the compounds. The magnetic stability obtained from GGA+U agrees well with the available experimental results. The thermodynamic stability of the three compounds shows that all the compounds are stable in both cubic and tetragonal structures. Using the energy difference method, we were able to calculate the exchange interactions and estimate the Curie temperature of the Rh2MnSn compound in the cubic structure. The phonon dispersion curves were investigated for the first time using the linear-response approach in the context of density functional perturbation theory. The results show that all the compounds are dynamically stable in their predicted phases. [ABSTRACT FROM AUTHOR]

• Physical characteristics of halide double perovskites Rb 2 TlSbX 6 (X = Cl, Br, I) were investigated by the DFT method. • The compounds are semiconductors with direct band gap. • IR Elast package is used for computation of elastic constant. • The structural, electronic, elastic, optical, and thermal properties were studied of the above stated compounds. To explore a good candidate for solar cell applications as an alternative to lead-independent materials, we calculated the structural and mechanical stability of the Rb 2 TlSbX 6 (X = Cl, Br, I) compounds with PBEsol potential. The optoelectronic and thermoelectric behaviors of these compounds are computed with TB-mBJ potential. Our results indicate that these materials possessed excellent structural, mechanical, and thermal stability on the basic values of their Goldsmith's, elastic parameters and negative formation energies. The dynamic stability is observed through phonon dispersion curve and found that all materials are dynamically stable. The computed values of Poisson and Pugh ratios and a positive value of Cauchy's pressure indicate the ductile nature of these materials. We observed the low direct bandgaps for Rb 2 TlSbCl 6 , (1.486 eV), Rb 2 TlSbBr 6 (2.07 eV), and Rb 2 TlSbI 6 (1.04 eV) unlike the majority of halide double perovskite family have large bandgap values in literature. In addition, the computed optical and thermoelectric characteristics of the Rb 2 TlSbX 6 (X = Cl, Br, I) materials show large values of absorption and optical conductivity with low reflectivity and energy loss at small energy ranges. According to these findings, all these halogen-based double perovskite materials have the potential to be employed as photovoltaic absorb materials in solar cell applications. Furthermore, the large values of the Seebeck coefficient, high-power factor and figure of merit (ZT) at room temperature also ensured their significance for thermoelectric generators. [ABSTRACT FROM AUTHOR]

In the current research, we focus on the computation of some physical properties including structural, electronic elastic, and optical properties of bariumbased BaXF3 (X= Hf, and Ta) fluoroperovskites using the DFT approach within the wien2k simulation package. Structurally it is found that these cubic crystal compounds are stable having a tolerance factor of 0.93 for BaHfF3 and 0.954 for BaTlF3. The most accurate exchange-correlation potential that is TB-mBJ is for the accurate measurement of electronic properties and the computations of electronic properties, i.e., from the band's structures and density of states (DOS) depict that these materials are metallic with having overlapping valence and conduction bands. Elastic properties are computed for both the selected compounds using the IRelast cubic elastic package and it is found that the compounds of interest are mechanically stable, anisotropic, ductile, and possess hardness for scratching. The optical properties within 0 eV to 40 eV incident photon energy were measured and we concluded that these materials are optically active at low energy ranges because they are metallic. In addition to that, high optical conductivity, absorption, and high reflectivity are observed for BaTF3 (T = Hf, and Ta) fluoroperovskite compounds. Herein we report for the first time the computational DFT-based precise results for both the compounds and from the reported work we deem the applications of selected fluoroperovskites will be relevant in many modern electronic and metallic industries. [ABSTRACT FROM AUTHOR]

The 18-valence electron ABX families of compounds have a variety of attractive physical properties. In this work, using the (FP-L/APW + lo) method on the basis of density functional theory, we have investigated the structural, electronic, elastic, thermodynamic, and transport properties of the HfXPb (X = Ni, Pd, Pt), in the cubic half-Heusler LiAlSi-type (F-43m) structure. The calculated elastic constants for these compounds showed that they are mechanically stable. Considering the Tran–Blaha-modified Becke–Johnson potential which provides a better description of the electronic structures, we have found that all three compounds are narrow-gap semiconductors. Furthermore, the thermoelectric properties depending on the chemical potential and charge carrier densities at different temperatures, 300 K, 600 K, and 900 K, are thus evaluated from the semi classical Boltzmann transport equation. The lattice thermal conductivity has been calculated by using a simplified model. Moreover, the most important thermodynamic properties, such as the Debye temperature, the thermal expansion coefficient, the heat capacity, and the entropy, have been predicted. [ABSTRACT FROM AUTHOR]

Using the full-potential linearized augmented plane wave (FP-LAPW) method, dependent on density functional theory, the simple cubic ternary fluoroperovskites XZnF3 (X = Al, Cs, Ga, In) compound properties, including structural, elastic, electronic, and optical, are calculated. To include the effect of exchange and correlation potentials, the generalized gradient approximation is applied for the optimization operation. This is identified, when we are changing the metallic cation specified as "X" when shifting to Al from Cs, the value of the bulk modulus is found to increase, showing the rigidity of a material. Depending upon the value of the bulk modulus, we can say that the compound AlZnF3 is harder and cannot be compressed as easily as compared to the other three compounds, which are having a lower value of the bulk modulus from AlZnF3. It is also found that the understudy compounds are mechanically well balanced and anisotropic. The determined value of the Poisson ratio, Cauchy pressure, and Pugh ratio shows our compounds have a ductile nature. From the computation of the band structure, it is found that the compound CsZnF3 is having an indirect band of 3.434 eV from (M-Γ), while the compounds AlZnF3, GaZnF3, and InZnF3 are found to have indirect band gaps of 2.425 eV, 3.665 eV, and 2.875 eV from (M-X), respectively. The optical properties are investigated for radiation up to 40 eV. The main optical spectra peaks are described as per the measured electronic structure. The above findings provide comprehensive insight into understanding the physical properties of Zn-based fluoroperovskites. [ABSTRACT FROM AUTHOR]

We present a theoretical comprehensive study which predicts and examines the outcomes of the structural, elastic, electronic, and optical properties of berylliumbased fluoroperovskite BeMF3 (M = Ti and V) compounds which was performed based on DFT (Density Functional Theory). The theoretical computation was done through the simulation package of WIEN2k, in which the implemented method of Full-Potential Linearized Augmented Plane Wave (FP-LAPW) was used. For the treatment of exchange correlation potential, the Generalized Gradient Approximation (GGA) was used for structural and elastic properties while the Modified Becke-Johnson (mBJ) exchange potential was used for a better understanding of the electronic and optical properties. Structural optimization was done with the Birch-Murnaghan equation of state, for the outcomes of fundamental optimized lattice parameters. The optimized 4.0833 Å and 4.0112 Å lattice constants were found for the BeTiF3 and BeVF3, respectively, and we found that both these compounds were structurally stable. For the computation of the elastic constants (ECs) of these crystals the IRelast package was used. Elastically these compounds were found to be mechanically stable because they satisfy the stability criteria, and are anisotropic and ductile in nature. Both the compounds of interest are metallic in nature and have overlapping valence and conduction bands. The TDOS and PDOS (total and partial density of state) plots were used to infer the relevance of the states contributed by each constituent element to the valence and conduction bands. Important optical properties, namely the dielectric function ε(ω), optical conductivity σ(ω), reflectivity R(ω), refractive index η(ω), and extinction coefficient k(ω) were examined and evaluated in a wide energy range (0-40 eV). Both the compounds were found to possess high optical conductivity in the low energy range, and because of these properties both the materials can be deemed to be likely to be of value in many modern electronic devices. To the best of our knowledge, this is the first precise theoretical insight into the some of the physical properties of BeMF3 (M = Ti and V) compounds. These properties are still to be verified experimentally. [ABSTRACT FROM AUTHOR]

Structural, electronic, magnetic and thermodynamic properties of TbInZ2 (Z = Cu, Ag, and Au) materials with two types of Heusler regular and inverse structures have been investigated in the framework of density functional theory. The non-magnetic, ferromagnetic and antiferromagnetic states are presented using first principles calculations. We applied the full potential linearized augmented plane waves method implemented in the Wien2k code, and the generalized gradient approximation was used to describe the exchange-correlation potential. The results obtained for the density of states and band structures reveal the metallic character of the studied compounds. The structural properties show that the most stable state for TbInZ2 (Z = Cu, Ag, and Au) compounds is the ferromagnetic state. The magnetic susceptibility and electrical Conductivity as a function of chemical potential are calculated using Perdew-Burke-Ernzerhof generalized gradient approximation. Furthermore, the variations of the lattice parameter, heat capacity, Debye temperature and entropy as a function of temperature have been investigated. [ABSTRACT FROM AUTHOR]

Prediction of new materials is crucial for the advancement of technology. Here, in this research work, the first-principle computation has been conducted utilizing the WIEN2K package to probe the structural, electronic, mechanical, and optical properties of barium-based chloroperovskites BaMCl3 (M = Ag, Cu) compounds. The optimized lattice constants are calculated for both compounds which are 9.90 Bohr for BaAgCl3 and 9.38 Bohr for BaCuCl3. To obtain better and more precise results for the electronic band’s structure, TDOS and PDOS (total and partial density of states), and the TB-mBJ potential approximation are employed. The indirect band gap (R–Γ) is found for both compounds having values of 1.173 eV and 2.30 eV for BaCuCl3 and BaAgCl3, respectively, which depicts its semiconducting nature. The calculation of elastic properties is conducted with IRelast code. The Cauchy pressure, Bulk modulus, Young’s modulus, Shear modulus, anisotropic ratio, Kleinman parameters, and Poisson’s ratio are calculated from the obtained elastic constants. The computation of elastic parameters indicates that the interested chloroperovskites are anisotropic, mechanically stable, hard to scratch, and ductile. From 0 eV to 40 eV incident photon energy ranges, the various optical parameter such as refractive index, absorption coefficient, dielectric function, reflectivity, extinction coefficient, and optical conductivity are analyzed. These compounds absorb maximum light within 5 to 25 eV incident photon energy. Hence, these materials are good light absorbers, therefore, they can be used in optoelectronic devices for high-frequency applications.

In the present paper, the structural, electronic, and linear optical properties of different phases of the gallium nitride (GaN) have been investigated. The zinc blende and wurtzite phases of the GaN have been studied using the full-potential linearized augmented plane wave method (FP-LAPW). In our study, many approximations have been used, such as the local density approximation (LDA), the generalized gradient approximation (GGA), the Engel and Vosko generalized gradient approximation (EV-GGA), and the modified Becke-Johnson (mBJ) potential exchange. As a result, we found a very good agreement with literature experimental results for the energy band gap using the mBJ approximation with a scaling factor of 98% and 80% for the zinc blende and wurtzite phases, respectively. [ABSTRACT FROM AUTHOR]

Structural, electronic, magnetic and optical properties of MFe 2 O 4 (M = Mn, Co, Ni) ferrites are studied by first-principles approach. MFe 2 O 4 ferrites exhibit stable structure in ferromagnetic phase. Density of states (DOS) and electronic band structures reveal that all ferrites show favorable spin polarization behavior in applications point-of-view. The CoFe 2 O 4 ferrite shows half-metallic ferromagnetic characteristics with direct band gap, E g = 0.713 eV in spin↑ state while NiFe 2 O 4 shows spin gapless ferromagnetic behavior (with E g = 0.0 at E F) in spin↑ state. The MnFe 2 O 4 ferrite is found to have magnetically conducting behavior. MFe 2 O 4 (M = Co, Ni) ferrites indicate 100% spin polarization at E F. The electronic band structures reveal electronic transition between O-2 p to Fe-3 d states in valence band (VB) or d-d transition between Fe-3 d valence and conduction bands. The optical properties shows that the MFe 2 O 4 (M = Mn, Co, Ni) ferrites exhibit transparent behavior to ultraviolet light indicating their suitability for use in optical filters and sensors. [ABSTRACT FROM AUTHOR]

A double perovskite BaSrMgTeO6 has been synthesized and characterized by physical techniques: X‐ray diffraction, and diffuse reflectance spectroscopy. It crystallizes at room temperature, in the cubic system with unit cell parameters: a=8.018Å (S.G Fm‐3m) and shows an almost perfect ordering between Mg2+ and Te6+ cations at the B substructure. Based on Density Functional Theory (DFT), and using full Potential‐linearized Augmented Plane Wave (FPLAPW) method with the Generalized Gradient Approximation (GGA), implemented in the Wien2k package, we have investigated electronic and optical properties of such material. The optical band gap obtained with GGA approximation is equal to 2.8 eV, which is in good agreement with our experimental results. We found that transmittance T is stable and reaches the average of 90% in both experimental and theoretical studies.

Nowadays, most of the ferroelectric materials have lead element in their formula. Having the lead element as an ingredient is hazardous both human life and environment. For safety reason, we have to replace lead-based compound with lead-free based one. Bismuth-based ferroelectric materials are one of the lead-free ferroelectric compounds. In this paper, we studied BiRhO3 compound belongs to bismuth-based family. We calculated and analyzed BiRhO3 physical properties such as electronic, structural and optical. According to our result, BiRhO3 is classified as a semiconductor with narrow band gap, 0.3 eV, with indirect transition. Moreover, its optical constant depends on choosing axes due to structure type.

We report high pressure study of CdS using the full-potential linear augmented plane wave (FP-LAPW) method based on density functional theory approach. In this approach, generalized gradient approximation (GGA) and Engel- Vosko generalized gradient approximation (EV-GGA) have been used for the exchange correlation potential in the calculations. The equilibrium lattice constant, electronic band structure, elastic constants, Debye temperature and melting temperature of binary solid CdS have been calculated under ambient and high pressure. Furthermore, the linear optical properties such as dielectric function, absorption, optical conductivity reflectivity, refractive index and energy loss are computed and analyzed in detail within the energy range up to 14 eV. The obtained results are in good agreement with earlier reported experimental and other theoretical results. [ABSTRACT FROM AUTHOR]

The Li2CaTa2O7 compound belongs to the Ruddlesden-Popper family of layered perovskites. First principle approximation was used to investigate the electronic band structure and optical properties of the compound for three phases. Independent of the studied compound's structural type, Li2CaTa2O7 has semiconductor behavior and direct transition. In addition, the forbidden energy band gap of the compound decreases with rising temperature, as expected. Furthermore, the 3d orbital of Ca contributes to the conduction band due to the crystal field effect. Moreover, the optical response of the chosen axes of the compound to incoming electromagnetic rays varies with phase transition. [ABSTRACT FROM AUTHOR]

Bu çalışmada WIEN2k bilgisayar programı kullanılarak ideal ve bükülmüş grafenin elektron yoğunluğu, durum yoğunluğu ve band yapısı elde edilmiştir. Burada ideal ve bükülmüş grafenin 2x2x1, 2x3x1 ve 3x2x1 boyutları çalışılmıştır. Her bir nanoşerit için 100, 200, 300 ve 500 k noktası kullanılmıştır. Elektronik durum yoğunluğu ve band yapıları, kristalin yarıiletken özellik sergilediğini göstermektedir. Yarıiletken özellik gösteren ideal ve ideal olmayan kristallerin yasak band aralığı, ideale göre ideal olmayan (bükülmüş) kristalde daha büyüktür. İdeal grafende gözlenen sıfıra çok yakın yasak band aralığı malzemenin metal özelliğine yatkınlığını ortaya koymaktadır. Ancak, genel anlamda, yarıiletken özelliğinin dikkat çektiğini gördüğümüz bükülmüş grafenin yasak band aralığı yaklaşık 0.7-1.9 eV aralığında değer almıştır.

The ab initio computer simulation of lattice parameters and local structure distortions caused by interstitial carbon atoms in the iron-carbon system has been carried out using WIEN2k software. For the calculations, the full-potential method of linearized augmented plane waves (LAPWs) taking into account the generalized gradient approximation of PBE-GGA was used in a supercell of 54 iron atoms with periodic boundary conditions. The carbon dissolution energy has been found to be 0.85 eV for bcc iron, and 0.79 eV for bct iron. The carbon-carbon interaction energies in the ferromagnetic bct iron have been calculated. It has been found that accounting for tetragonal distortions considerably changes the interaction energy of carbon atoms in comparison with that of the bcc iron. Both the maximum degree of tetragonality of iron and the maximum attraction of carbon atoms have been observed for the case of carbon atoms placed in octahedral pores of the same type. If carbon atoms are in different types of octahedral pores, the tetragonal distortion of the lattice is weak. The obtained results are in good agreement with the Zener-Khachaturyan hypothesis and experimental data of Kurdyumov. [ABSTRACT FROM AUTHOR]

The literature data on the interactions between carbon atoms and the methods of calculating its activity in the γ-iron lattice have been analyzed. Both statistical thermodynamic results and the data obtained by methods of computer simulation have been considered. To compare the available results, the simulation of the carbon activity in austenite using the Monte Carlo method has been carried out. It has been shown that the experimental curve of the concentration dependence of the carbon activity can be reproduced using a large number of strongly differing energies of interactions between carbon atoms in the first two coordination shells. Thus, the problem of determining the parameters of the С-С interaction in fcc iron according to the data on the activity is mathematically ill posed and first-principles calculations are necessary. It has been shown that, at carbon concentrations of up to 7 at %, the approximate statistical theories lead to accurate results. An analysis of the results of an ab initio simulation showed that the inclusion of the interaction between carbon atoms in the third and fourth coordination shells hardly affect the carbon activity. [ABSTRACT FROM AUTHOR]

First principles calculations were carried out to examine the spin-polarized electronic and optical characteristics of novel Ba 2 TaXO 6 (X = Co, Fe, In) double perovskites in the monoclinic phase, employing the full-potential linearized augmented plane wave technique (FP-LAPW) based on the density functional theory (DFT). To calculate the total energy, the Perdew-Burke-Ernzerhof generalized gradient approximation (PBE-GGA) were used. The electronic study with the TB-mBJ approach shows a metallic nature for Ba 2 TaCoO 6 and a half-metallic nature for Ba 2 TaFeO 6 and Ba 2 TaInO 6 materials. The calculated density of states, nearly show similar features for all the materials. The PDOS were calculated, which displays the contribution of several electronic states for these compounds in the distribution. Additionally, in the optical spectra, the dielectric functions, absorption coefficients, refractive indexes, extinction coefficients, energy loss function, and reflectivity parameters were calculated in the energy range 0–14 eV. The optical parameters demonstrate that the materials are the potential candidates for opto-electronics devices. Figure: Spin-Polarized optical parameters for Ba 2 TaFeO 6 double perovskite. [Display omitted] • A metallic nature for Ba 2 TaCoO 6 and a half-metallic nature for Ba 2 TaFeO 6 and Ba 2 TaInO 6 is observed. • The calculated density of states, nearly display a similarity trend. • The energy loss was maximum in energy region 0.6–6.0 eV range. • The peaks in ε 2 (ω) are linked to various inter-band transitions. • These double perovskites show substantial absorption in UV region. [ABSTRACT FROM AUTHOR]