Lead-free double halide perovskites like Rb2Ag(Ga/In)Br-6 have demonstrated themselves potential candidates in solar cell research owing to their environmental friendliness, stability, and exceptional performance. This study comprehensively analyzes the structural, mechanical, optoelectronic and optical coating features, as well as thermodynamic and thermoelectric properties of two Rb2AgGaBr6 and Rb2AgInBr6 compounds. Using the Wien2k code with GGA + mBJ exchange-correlation potentials, we confirm their structural stability in cubic phase Fm-3m and identifying them as direct band gap semiconductors (Gamma -> Gamma) of 0.38 eV and 1.0644 eV, respectively. Then, optical analysis reveals broad absorption bands across visible and ultraviolet wavelengths, making them suitable for photovoltaic absorbers. Finally, the thermoelectric investigations under varying temperatures show favourable properties, such as a high Seebeck coefficient with poor electronic thermal conductivity. This also yields exceptional value (0.96 and 0.994 for Rb2AgGaBr6, Rb2AgInBr6, respectively) of figure of merit (ZT) at room temperature and chemical potential mu-mu 0 = - 0.09eV near the Fermi energy level, enhancing their potential for thermoelectric applications. These findings underscore the versatility and promising future of Rb2Ag(Ga/In)Br-6 as important semiconductors processing for optoelectronic, thermoelectric, and mechanical devices.

In this research work, we synthesized a Schiff base derivative, N,N-dimethyl-4-{[(4-nitrophenyl)imino]-methyl}aniline, denoted as (n1). The molecule (n1) was characterized using spectroscopic analyses, including FT-IR, NMR 1H, and 13C. Our compound (n1) is an unsaturated molecule, consisting of two benzylic rings connected by a methylimine bridge. The resulting system comprises seven alternating π bonds. At both ends of (n1) and in the para position, there are the N(CH3)2 group with a strong electron-donating effect and the NO2 group with a strong electron-accepting effect. The molecular structure of our compound prompted us to evaluate and study its properties in the field of NLO. The assessment of NLO properties is conducted by determining the Egap and employing density functional theory (DFT) quantum chemistry studies. The optical gap of (n1), measured using the Tauc method, is found to be 2.7 eV, serving as a reference value for the choice of the DFT functional in theoretical calculations. Quantum chemistry studies were carried out using Gaussian09 software, and the results were visualized with GaussView05. CAM-B3lyp functional was chosen for theoretical calculations due to its close agreement with experimental values. The studies confirm that (n1) exhibits significant NLO properties. Additionally, NBO (Natural Bond Orbital) analyses provide insight into the mechanism and trajectory of intramolecular charge transfer in (n1).

In this research work, we investigate phonon modes related to the first Brillouin zone centre of double perovskites Ba 2 MgWO 6 , Ba 2 ZnWO 6, and Ba 2 CdWO 6 . Besides, Debye temperature, elastic constants, and elastic properties are also evaluated. These investigations are carried out by employing a theoretical model based on the six parameters bond-bending force constant. From our calculations, we found the strength of the first-neighbor interaction is higher as compared to the second and third neighbor’s interatomic interactions. Our computed results corresponding to Young, Bulk, and Shear moduli and Debye temperature are found in a sequence Ba 2 CdWO 6 >Ba 2 ZnWO 6 >Ba 2 MgWO 6 . Moreover, all the examined double perovskite compounds reveal their ductile and elastically anisotropic nature. Our predicted results for frequencies of zone-centre phonons and elastic constants also show nice agreement with previously reported results.

The full potential linearized augmented plane waves (FP-LAPW) approach is used to investigate the structural, electronic, and magnetic properties of full-Heusler alloys X2CrAl (X = Co and Mn) and their quaternary com-pounds MnCoCrAl and CoMnCrAl. The density of states (DOS) of Co2CrAl, Mn2CrAl, and related quaternary compounds reveal the existence of energy band gaps with half-metallic behavior based on GGA and mBJ exchange-correlation potential.All full-Heusler materials and their quaternary compounds have total magnetic moments that agree well with the Slater Pauling rule. Mechanical properties of these compounds are also researched, including bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and Pugh's ratios, and all studied compounds display mechanical stability under the mechanical stability criterion. Our findings provide experimental researchers with suggestions for synthesizing promising materials for future spintronic applications.& nbsp;

Heusler materials have shown a ground-breaking role in material research because of their widespread applicability in modern technologies and multi-dimensional properties. In this study, the pressure effects on the structural, electronic, and magnetic properties of Mn(2)YAN (Y = Ru, Rh, and Pd) Heusler alloys are investigated. This study is carried out by employing a state-of-the-art first-principles computational approach called "full potential (FP) linearized (L) augmented plane wave plus local orbital (APW + lo)" as designed using density functional theory (DFT), and executed in WIEN2k computational code. The computed results for the lattice constants have been found to be in fairly good agreement with previously reported results in the literature. The results show that the Mn2RuSn, Mn2RhSn, and Mn2PdSn compounds are stable in the Hg2CuTi-type structure. Furthermore, under the pressure effect, the Mn2RuSn, Mn2RhSn, and Mn2PdSn compounds become half-metals at about 10 GPa, 10 GPa, and 20 GPa, respectively.

Eight push–pull systems involving containing four transition metals (iron, ruthenium, cobalt, and nickel), metallocenes as donor groups, cyanoacrylate as electron attractor group, and thiophene-N = N- pyrimidine derivatives as π-conjugated bridges were designed and studied using DFT and TD-DFT methods involving B3LYP and CAM-B3LYP functionals combined with the cc-pVDZ/LANL2DZ basis sets. The main purpose of this work is to determine the effect of metallocene in improving the photosensitization property of such chromophores. This was done by calculating their light-harvesting efficiency LHE as well as other properties employed for DSSC application. The considered dyes were first studied in the gas phase, then in the presence of TiO2 nanoparticles representing the semi-conductor, and finally in the presence of a specific implicit solvent. The presence of iron as metal involved in the metallocene group supplemented by extending the π-conjugated bridge by a cyanovinyl spacer was demonstrated so as to give the most optimal response taking into account the lower cost and toxicity as well as the friendliness to the environment of iron as metal.

The structural, electronic and optical properties for fluoro-perovskite NaXF3 (X = Ca and Sr) compounds have calculated by WIEN2k code based on full potential linearized augmented plane wave (FP-LAPW) approach within density functional theory (DFT). To perform the total energy calculations, exchange-correlation energy/potential functional has been utilized into generalized gradient approximation (GGA) and local density approximation (LDA). Our evaluated results like equilibrium lattice constants, bulk moduli, and their pressure derivatives are in agreement with the available data. The electronic band structure calculation has revealed an indirect band-gap nature of NaCaF3, while NaSrF3 has direct band gap. Total and partial densities of states confirm the degree of localized electrons in different bands. The optical transitions in NaCaF3 and NaSrF3 compounds were identified by assigning corresponding peaks obtained from the dispersion relation for the imaginary part of the dielectric function. The thermodynamic properties were calculated using quasi-harmonic Debye model to account lattice vibrations. In addition, the influence of temperature and pressure effects was analyzed on bulk modulus, lattice constant, heat capacities and Debye temperature.

The structural, elastic, electronic, optical, and thermodynamic properties of the \(\hbox {ZnAl}_{2}\hbox {S}_{4 }\) compound are calculated in the frame work of the density functional theory where the calculated structural parameters are found to be in good agreement with the experimental data and other theoretical calculations. The calculations show that the material is elastically stable and isotropic. Furthermore, the calculated band gap is observed to be wide and direct and is comparable with earlier experimental data as well as with other theoretical calculations; hence, it is an optically active material for optoelectronic applications. In addition, the compound is found to have mixed ionic and covalent bonding nature. The optical nature of the compound is described in terms of the complex dielectric function, complex refractive index, reflectivity, and energy loss function. On the other hand, variation of the unit cell volume, bulk modulus, heat capacity, and Debye temperature are described as a function of temperature at different pressures for the \(\hbox {ZnAl}_{2}\hbox {S}_{4}\) compound.

The structural, elastic, electronic, optical, and thermodynamic properties of the ZnAl_2S_4 compound are calculated in the frame work of the density functional theory where the calculated structural parameters are found to be in good agreement with the experimental data and other theoretical calculations. The calculations show that the material is elastically stable and isotropic. Furthermore, the calculated band gap is observed to be wide and direct and is comparable with earlier experimental data as well as with other theoretical calculations; hence, it is an optically active material for optoelectronic applications. In addition, the compound is found to have mixed ionic and covalent bonding nature. The optical nature of the compound is described in terms of the complex dielectric function, complex refractive index, reflectivity, and energy loss function. On the other hand, variation of the unit cell volume, bulk modulus, heat capacity, and Debye temperature are described as a function of temperature at different pressures for the ZnAl_2S_4 compound.

We have investigated the structural, elastic, electronic, optical and thermal properties of CsBaF3 perovskite using the full-potential linearized augmented plane wave method within the generalized gradient approximation and the local density approximation. Moreover, the modified Becke Johnson potential (TB-mBJ) was also applied to improve the electronic band structure calculations. The ground state properties such as lattice parameter, bulk modulus and its pressure derivative were calculated and the results are compared with the available theoretical data. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young's modulus and Poisson's ratio are obtained for the first time. Electronic and bonding properties are discussed from the calculations of band structure, density of states and electron charge density. The contribution of the different bands was analyzed from the total and partial density of states curves. The different interband transitions have been determined from the imaginary part of the dielectric function. The thermal effect on the volume, bulk modulus, heat capacities Cv and the Debye temperature was predicted using the quasi-harmonic Debye model, in which the lattice vibrations are taken into account.

The mechanical, optoelectronic, and thermodynamic properties of carbon silicon nitride spinel compound have been investigated using density functional theory. The exchange–correlation potential was treated with the local density approximation (LDA) and the generalized gradient approximation of Perdew–Burke and Ernzerhof (PBE-GGA). In addition, the Engel–Vosko generalized gradient approximation (EV-GGA) and the modified Becke–Johnson potential (TB-mBJ) were also applied to improve the electronic band structure calculations. The ground state properties, including lattice constants and bulk modulus, are in fairly good agreement with the available theoretical data. The elastic constants, Young’s modulus, shear modulus, and Poisson’s ratio have been determined by using the variation of the total energy with strain. From the elastic parameters, it is inferred that this compound is brittle in nature. The results of the electronic band structure show that CSi2N4 has a direct energy band gap (Γ–Γ). The TB-mBJ approximation yields larger fundamental band gaps compared to those of LDA, PBE-GGA, and EV-GGA. In addition, we have calculated the optical properties, namely, the real and the imaginary parts of the dielectric function, refractive index, extinction coefficient, reflectivity, and energy loss function for radiation up to 40.0 eV. Using the quasi-harmonic Debye model which considers the phononic effects, the effect of pressure P and temperature T on the lattice parameter, bulk modulus, thermal expansion coefficient, Debye temperature, and the heat capacity for this compound were investigated for the first time.

Density functional theory (DFT) is performed to study the structural, electronic and optical properties of cubic fluoroperovskite AMF3( A = Cs ; M = Ca and Sr ) compounds. The calculations are based on the total-energy calculations within the full-potential linearized augmented plane wave (FP-LAPW) method. The exchange-correlation potential is treated by local density approximation (LDA) and generalized gradient approximation (GGA). The structural properties, including lattice constants, bulk modulus and their pressure derivatives are in very good agreement with the available experimental and theoretical data. The calculations of the electronic band structure, density of states and charge density reveal that compounds are both ionic insulators. The optical properties (namely: the real and the imaginary parts of the dielectric function ε(ω), the refractive index n(ω) and the extinction coefficient k(ω)) were calculated for radiation up to 40.0 eV.

The structural and electronic properties of the cubic fluoroperoveskite \(\text{ CsBeF}_{3}\) and \(\text{ CsMgF}_{3}\) have been investigated using the full-potential-linearized augmented plane wave method within the density functional theory. The exchange-correlation potential was treated with the local density approximation and the generalized gradient approximation. The calculations of the electronic band structures show that \(\text{ CsBeF}_{3 }\) has an indirect bandgap, whereas \(\text{ CsMgF}_{3}\) has a direct bandgap. Through the quasi-harmonic Debye model, in which the phononic effects are considered, the effect of pressure \(P\) and temperature \(T\) on the lattice parameter, bulk modulus, thermal expansion coefficient, Debye temperature, and the heat capacity for \(\text{ CsBeF}_{3}\) and \(\text{ CsMgF}_{3}\) compounds are investigated for the first time.

In order to get a good overall description of the structural, electronic and optical properties of ternary chalcopyrite semiconductors especially for ZnSiAs2 and CdSiAs2, they have been calculated self consistently using the full potential augmented plane wave plus local orbital method (FPAPW+lo). The calculations are presented within the local density approximation (LDA), where we clarify the electronic and optical properties for both compounds. Since, we prove the existence of the direct band gap and also the efficiency of the method to give more details about the optical properties. We found that the most important features of the band gap is pseudo-direct for ZnSiAs2, and direct for CdSiAs2; then the contribution of the different transitions peaks are analyzed from the imaginary part of the dielectric function and the reflectivity spectra.

We present ab initio calculations for CaS, CaSe and CaTe, in the B1 (NaCl) and B2 (CsCl) phase, by means of accurate first principle total energy calculations using the all-electron full-potential linear muffin-tin orbital method FP-LMTO.The calculations are presented within the local density approximation (LDA). Results are given for structural, electronic and elastic. Good agreement is found with experimental data. The efficiency and the accuracy of this method are so appreciated to predict some properties of this kind of materials.