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Strain engineering is a powerful technique for controlling the performance of semiconductor ceramic systems. In this article, the effect of strain engineering, specifically biaxial compressive and tensile strains, on the bonding characteristics, structure, electronic, and optical properties of nonplanar phosphorene‐like (NPP) ZnS ceramic nanolayers was investigated using density functional theory. It was observed that this ceramic exhibits greater stability under significant tensile strains. The structural stability of NPP‐ZnS ceramic, both with and without biaxial strain, was confirmed by its negative formation energy. Biaxial strain strongly influences the electronic band structure of NPP‐ZnS ceramic nanolayers, leading to a transformation from a direct band gap to an indirect gap under tensile strain. Additionally, the bandgap decreases under compressive strain, while it slightly increases under tensile strain. Various optical properties, including refractive index, extinction coefficient, absorption, reflectivity, optical conductivity, and optical susceptibility, were calculated. Biaxial compressive and tensile strains alter the optical properties, shifting them to higher or lower frequencies. NPP‐ZnS ceramic nanolayers exhibit high optical absorption in the UV range, which can be further enhanced by biaxial strain. Furthermore, under increasing compressive strain, the absorption edge moves toward higher energies. This improvement in optical absorption expands the potential applications of NPP‐ZnS ceramic nanolayers in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Inbuilt high energy band gap and resistivity cause harm to the intrinsic molybdenum trioxide (MoO3) for utilizing it directly in gas sensing and optoelectronic devices. Doping with transition metal ions can be an optimistic solution to these problems. By doping four side of modification of a material is possible. At first, doping can curtail the width of the energy band of semiconductor materials, thereby largely boosting the photo-sensitivity of the material and intensifying the light consumption that is more suitable for anti-laser devices and light source substances. The second is that doping can widen the material's band gap, which can significantly reduce the purities of the substance, improve absorbance, and make it suitable for strong interference semiconductor films and aperture materials. Third, changing the material's charge carrier density and effective mass can significantly improve conductivity. This is mostly relevant for conductive devices and photosensitive materials. Finally, changing the material's valance electron location influences the magnetic moment created by the spin of elementary particles in the entire system, allowing the magnetic characteristics of the substance to be regulated, which is especially useful for diluted magnetic semiconductor (DMS) materials. The investigation report of the structural, electrical, and optical characteristics of Cobalt (Co)-doped orthorhombic-phase MoO3 utilizing plane-wave pseudo-potential technique based on first-principles computation is presented in this paper. The computation has been executed using density a functional theory (DFT)-based CASTEP computer program with the generalized gradient approximation (GGA) together with the Perdue-Burke-Ernzerhof (PBE) exchange–correlation function. Acquired structural parameters present good consistency with the former reported experimental data. The resultant electronic band structure reveals that pure MoO3 shows an indirect energy band gap of 1.873 eV/2.312 eV whereas Co doping causes band narrowing of about 0.94 eV/1.36 eV with PBE/HSE techniques. The total and partial density of states (PDOS) have been studied comparatively, for pure and Co-doped MoO3, respectively. The absorption coefficient, loss function, reflectivity, refractive index, extinction coefficient, dielectric function, along with optical conductivity have also been determined to analyze the optical properties of Co-doped MoO3. Co-doped MoO3 offers higher conductivity while decreasing resistivity, compared to the undoped case. The present study ensures that Co-doped α- MoO3 can be competently employed as a functional material in gas sensing and optoelectronic devices. [ABSTRACT FROM AUTHOR]

First principles calculations of the structural, electronic and optical properties of GaSb, InSb and their ternary Ga 1 - x In x Sb alloys (x = 0.25, 0.50 and 0.75) have been performed using the full-potential linear muffin-tin orbital (FP-LAPW) method within density functional theory (DFT). The generalized gradient approximation and modified Becke and Janson functional with local density approximation (mBJ–LDA) are utilized for the treatment of exchange and correlation potentials. The results show the calculated lattice constants increase linearity with increasing the In concentration. The electronic band structure indicates that these alloys are direct band gap semiconductors for all the values of x and the band gap decreases as x increases from x = 0 to x = 1. The results also show that the there is a non-linear dependence of the band gap on composition x in Ga 1 - x In x Sb alloys. Regarding optical properties, the real and imaginary parts of the dielectric function have been calculated. The results show that the static dielectric constant increases with increase in concentration of In, consistent with reduction in energy band gap. The onset point and major peaks in the imaginary parts of the dielectric function spectra are identified for the Ga 1 - x In x Sb alloys and shown that they are related to the corresponding band gap values. The results also show that for energy values higher than ≅ 4 eV, the electromagnetic wave transition through Ga 1 - x In x Sb alloys is nearly zero. [ABSTRACT FROM AUTHOR]

Context: The 2D AlN/BN planer heterostructure is a promising wide band gap semiconductor, but systematic studies of its bandgap and optical characteristics under applied strain are scarce. Here, the engineering property of 2D AlN/BN comprising bandgap nature transition and optical absorption capability (from unstrained to strained) have been investigated using density functional theory calculations. The formation energy calculations confirm the stability of the simulated nanoheterostructure. The electronic band structure calculations demonstrate that nanoheterostructure is an indirect bandgap material with a large bandgap of 5.26 eV, which can be modified effectively by applying strain. According to the calculations, the transition from indirect to direct band gap behavior has been observed at +15% biaxial strain with 2.71 eV band gap energy. Meanwhile, calculations for optical absorption and dielectric function reveal that the system has significant absorption peaks in the ultraviolet region which are very sensitive to applied strain. As strain increases, the first absorption peaks are shifted towards a lower energy range from 5.73 eV (Ꜫ= 0 %) to 3.76 eV (Ꜫ = +15%), which features an enhancement of optical absorption for solar and solar-blind regions. Furthermore, we determined that the band edge positions in 2D AlN/BN straddled the water redox potential under strain, indicating its effectiveness as a proficient photocatalyst. These characteristics make 2D AlN/BN planer nanoheterostructure a promising candidate for applications in optoelectronics and photocatalytic water splitting performance. Methods: First principles computations based on density functional theory were employed to carry out all the calculations with a self-consistent approach. For solving the Kohn-Sham equations, the first principles dependent full-potential linearized augmented plane wave scheme were adopted. For addressing the exchange-correlation effects, the generalized gradient approximation of PBEsol functional was used. To prevent interaction between the periodic images, we have inserted a vacuum region of 10 Å in the z-direction. Non-negligible weak dispersion corrections in nanoheterostructure were considered by using the DFT-D3 method of Grimme's. The locally modified Becke-Johnson (lmBJ) exchange potential has also been applied to compute electronic and optical properties in this research to obtain more accurate information. [ABSTRACT FROM AUTHOR]

Context: Two-dimensional (2D) nanoheterostructures of materials, integrating various phase or materials into a single nanosheet have stimulated large-scale research interest for designing novel two dimensional devices. In contemporary analysis present work, we examined the structural and electronic properties of the isolated 2D BN and GaN monolayers. We have investigated the structural stability and optoelectronic and photocatalytic response of the g-GaN/BN nanoheterostructure along with its response to strain. Nanoheterostructure g-GaN/BN is predicted to be a direct bandgap semiconductor with wide gap of 4.45 eV, whose value can be effectively modulated by applied strain ( ϵ) , ranging from 4.55 (ϵ = − 4%) to 3.58 eV (ϵ = 8%). We also discovered that the tensile strain of 8% can substantially tune the direct bandgap of nanoheterostructure to indirect band gap nature. Even more important, the biaxial tensile strain engineering accentuates an enhancement of optical absorption in the UV region, broadening the light harvesting of the g-GaN/BN nanoheterostructure with the shifting of first absorption peak from 4.64 (ϵ = − 4%) to 3.71 eV (ϵ = 8%). Furthermore, strain-tuned band edge potentials arrangement perfectly fits the water reduction and oxidation redox potentials. Our findings portend that the g-GaN/BN nanoheterostructure has application in prospective nanoscale optoelectronic devices and photocatalytic hydrogen evolution system. Methods: First principles calculations in this study are performed using density functional theory. Generalized gradient approximation within PBEsol functional employed to address the electron–electron exchange–correlation effects. For avoiding periodic interactions between the layers, we have inserted a vacuum region of thickness 10 Å in the z-direction. For ensuring the convergence accuracy of the computed results, convergence criteria of the iteration process is set to be 0.0001 eV. Local modified Becke–Johnson, a semi local functional, is applied for calculating electronic and optical properties for more accuracy of results. As in layered 2D nanoheterostructure, a factual depiction of the van der Waals interactions cannot be provided by conventional DFT techniques. Accordingly, in order to incorporate these interactions, we had employed the dispersion correction method of Grimme's. [ABSTRACT FROM AUTHOR]

The double perovskites have excellent photocatalytic capabilities and could be used for water splitting purposes. Herein, we used density functional theory (DFT) computations to inspect the compound's characteristics. Generalized gradient approximation (GGA)-Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional with compounds space group 123 (p4/mmm) are used for investigations. According to the findings, The structural characteristics show that these compounds have a tetragonal nature (a = b≠c) with 16 atoms. The electronic band structures indicate that all compounds have a semiconductor nature with an indirect energy bandgap E g of 2.25 eV, 2.92 eV, and 2.31 eV for RbCa 2 Ti 3 O 10 , RbMg 2 Zr 3 O 10 , and RbMg 2 Ti 3 O 10 , respectively. According to analyses of the Mulliken atomic (MA) populations, every chemical has complex bonding with both covalent and ionic characteristics. The elastic characteristics of the perovskite revealed that it is elastically anisotropic and mechanically stable. The calculated values of Pugh's (1.48, 1.91, 4.42) and Poisson's (0.22, 0.28, 0.39) ratios indicate that the substances RbCa 2 Ti 3 O 10 and RbMg 2 (Zr/Ti) 3 O 10 under study are brittle and ductile by nature. As a result, we anticipate that these compounds are valuable in the growth of high-performance photocatalytic devices for water splitting for various applications like producing hydrogen and oxygen. • All compounds display semiconductor characteristics with an indirect energy bandgap (Eg). • Mulliken atomic (MA) population analyses reveal complex bonding with both covalent and ionic characteristics. • The perovskite is elastically anisotropic and mechanically stable. • Pugh's ratios and Poisson's ratios suggest that RbCa2Ti3O10 and RbMg2(Zr/Ti)3O10 are brittle and ductile by nature. • These compounds can contribute to the development of high-performance photocatalytic devices for water splitting. [ABSTRACT FROM AUTHOR]

We study structural, electronic and optical properties of inorganic leadfree halide perovskites RbGeX3 (X = Cl, Br and I) under hydrostatic pressure, which could facilitate development of new optoelectronic and solar-cell technologies. ab initio first-principles calculations are employed based on the generalized gradient approximation within the framework of density functional theory. We demonstrate that the bandgap of our perovskites decreases with increasing pressure. At a given pressure, the bandgap becomes narrower when the halogen atom is changed from Cl to I. We also examine the density of states and demonstrate that the energy levels near the Fermi level change significantly under pressure. The optical properties are calculated using the density functional perturbation theory and the Kramers-Kronig relation. The optical parameters such as the real and imaginary parts of the dielectric function, the refractive index and the absorption coefficient are calculated under different pressures. [ABSTRACT FROM AUTHOR]

The full potential linearized augmented plane wave (FP-LAPW) approach based on the density functional theory (DFT) is employed to know the effect of Co doping on the electronic, optical, and magnetic characteristics of BaTi1-xCoxO3 at x= 8.33%, 16.66%, 25%, and 50%. The computed spin-polarized electronic band structure (BS) and the density of states (DOS) elucidate that the BaTi1-xCoxO3 compound has a ferromagnetic semiconductor behavior at all doping concentrations. The results indicate that the magnetic moment in BaTi1-xCoxO3 is found due to the p-d hybrid orbitals of Co. Moreover, the optical features of the Co-doped BTO compound are evaluated by analyzing the refractive index, reflectivity, absorption coefficient, optical conductivity, and dielectric constant under different concentrations. The outcomes revealed that the BaTi1-xCoxO3 compound is a good candidate for spintronics and optoelectronic applications. [ABSTRACT FROM AUTHOR]

MXene is regarded as an innovative 2D nanomaterial for energy storage applications. In this study, we calculated the structural, electronic, optical, and mechanical properties of Ti3X2 (X = C, N, P, S) MXene materials using the CASTEP simulation package based on the density functional theory. The calculated lattice parameters at zero pressure are in good agreement with the previously reported results. We also calculate the studied materials' formation energy to check the compounds' stability. The negative formation energy values suggest that Ti3X2 (X = C, N, P, S) compounds are stable and can be synthesized experimentally. The electronic properties, i.e., electronic band structures, total density of state and partial density of state, suggest that Ti3X2 (X = C, N, P, S) compounds are metallic. To understand the behavior of light scattering, we calculate the optical properties of Ti3X2 (X = C, N, P, S). The maximum reflectivity occurs at 62%, 56%, 49%, and 33% for Ti3P2, Ti3C2, Ti3N2 and Ti3S2, respectively. Optical properties also suggest the metallic nature of studied materials. Mechanical properties suggest that Ti3C2 is ductile behavior and Ti3N2, Ti3P2, and Ti3S2 are brittle behavior. [ABSTRACT FROM AUTHOR]

In recent times transition metal ternary borides with layered structure have attracted much attention of the materials science community. In this study, we have used density functional theory (DFT) based first-principles investigation of the physical properties of prospective NbAlB compound for the first time. From the analysis of the cohesive energy and enthalpy of formation, it was found that NbAlB is expected to be chemically stable. The physical properties of NbAlB have been compared and contrasted with those obtained for MoAlB. Both these MAB phases are elastically anisotropic, mechanically stable, machinable and brittle materials. Structural and elastic features reflect the layered features. The estimated hardness of NbAlB is 19.0 GPa comparable to that of MoAlB (20.8 GPa) suggesting that predicted NbAlB is a hard compound and is suitable for heavy duty industrial applications. NbAlB is more machinable than MoAlB. Electronic band structure calculations reveal conventional metallic behavior with the electronic density of states at the Fermi level arising mainly due to the Nb 4d orbitals in NbAlB. The electronic density of states at the Fermi level is significantly higher in NbAlB in comparison to MoAlB, indicating that NbAlB is expected to exhibit higher level of electrical conductivity. Electronic dispersion is highly anisotropic for both MoAlB and NbAlB with substantially large electronic effective masses in the out-of-plane directions. The bonding features have been elucidated via the analysis of the band structure and charge density distribution. Both the compounds have mixed covalent, ionic and metallic bonding characteristics. The Fermi surfaces of MoAlB and NbAlB consists of electron and hole like sheets. The Debye temperatures of MoAlB and NbAlB are comparable. The estimated melting temperature of NbAlB is somewhat lower than that of MoAlB. NbAlB shows excellent reflection characteristics suitable to be used as an efficient solar reflector. NbAlB is also expected to absorb ultraviolet radiation very effectively. Unlike elastic, bonding, and electronic anisotropy, the optical spectra are fairly isotropic for NbAlB with respect to the polarization of the incident electric field.

The structural, electronic and optical properties of monoclinic Sr2NiTeO6 double perovskite have been studied using corrected density functional theory–local density approximation with applying of Hubbard U corrected energy (DFT–LDA + U) method in plane-wave pseudopotential basis. The influence of on-site Coulomb interaction on structural, electronic and optical properties of Sr2NiTeO6 double perovskite compound, which consists of strongly localized Ni 3d electrons, were investigated. The highly Coulomb repulsion between electrons was corrected using Hubbard U parameter, varying from 0 to 8 eV for Ni 3d orbitals. The calculated results demonstrated that Sr2NiTeO6 double perovskite was sensitive to the change in U values. The optimized structural properties give a good agreement with experiment and other calculation data with lattice parameters a = 5.673 Å, b = 5.565 Å, c = 7.847 Å, α = 89.999°, β = 90.257° and γ = 90.000°. The DFT–LDA + U predicted the calculated electronic band structure of Sr2NiTeO6 was showed metallic behaviour (0 and 2 eV) and insulator behaviour (4, 6 and 8 eV). The density of state (DOS) shows that there was a significant effect on hybridization of Ni 3d and O 2p states at the conduction and valence band, respectively. Moreover, the results of optical studies such as dielectric function, absorption and reflectivity were found significant to the variation of U values applied indicates that the U values give a better description on the electronic localization of Ni 3d states.

Structural, electronic and optical properties of strained CdS monolayer and bilayer structures are studied to examine the possibility of controlling their properties for application in the field of nano-devices. First-principles density functional theory (DFT) calculations are done as implemented in SIESTA code that uses a pseudopotential and a numerical nano-orbital basis set. Exchange correlation energies were described using the general gradient approximation (GGA) in the form of Perdew–Burke–Ernzerhof (PBE) functional. We have found that the electronic band structure of monolayer and bilayer CdS is quite sensitive to biaxial strain, and as a result bandgap energy can be tuned over a wide range with compressive and tensile strains. While both the monolayer and bilayer structures maintain the direct bandgap nature of the relaxed structure even under compressive strain, tensile strain transforms the material into indirect gap semiconductors with degenerate electronic band structure. It is found that effective masses can also be controlled with biaxial strain, and hence carrier mobility can be improved in the process. Our DFT calculations also predict that in addition to tuning the optical absorption, intensity of direct bandgap absorption in these two structures can be enhanced under tensile strain. [ABSTRACT FROM AUTHOR]

A first principle Density Functional Theory (DFT) analysis was applied to investigate the structural, electronic, and optical properties of cubic perovskites KXB 3 (X= Ge, Sn; B= Cl, Br). Using the computational code WIEN2K, the corresponding properties have been studied through the use of Generalized Gradient Approximation. Experimental values of lattice constants are consistent with those derived from calculations. The wide direct band gap of 1.5–2 eV (M-M) is confirmed by the electronic band structure. This behavior suggests that the compounds under study are semiconducting KXB 3 (X= Ge, Sn; B= Cl, Br) halide perovskite materials are a promising alternative to photovoltaic semiconductors because of their appealing optical properties, as confirmed by a variety of optical properties. Because of their advancement in perovskites, these materials can captivate the world. So, these perovskites materials can captivate world due to its advancement in Opto-electronic application especially in photovoltaic area. [ABSTRACT FROM AUTHOR]

• The structural, elastic, electronic, magnetic, and optical properties of vacancy-ordered Rb 2 TcCl 6 have been thoroughly examined through the use of first-principles calculations. • The stability of Rb 2 TcCl 6 is demonstrated by the formation energy, optimization curves and phonon curves. • The spin-plarized electronic band structure and density of states (DOS) predict the semiconductor nature in both spin states. • The obtained magnetic moments for Rb 2 TcCl 6 reveal the potential of for spintronics. • An optical band gap with maximum absorption reveals that this compound is also useful for the application in optoelectronics. Due to their versatile properties, vacancy-ordered double perovskites offer a wide range of potential uses due to their versatile properties. We have thoroughly examined the physical characteristics of vacancy-ordered Rb 2 TcCl 6 in its cubic phase by employing the spin-polarized computations. The ground state energy and optimum structural parameters are obtained in order to assess the structural stability, which is further validated using the tolerance factor and formation energy values. The ductile character of Rb 2 TcCl 6 is revealed by a comprehensive evaluation of mechanical properties. Vickers hardness factor suggests that Rb 2 TcCl 6 can withstand against pressure-induced disturbance more strongly. A direct bandgap for spin-up is measured up to 2.33 eV, while for spin-dn it is 2.02 eV. According to the magnetic moments of 2.69 μ B , Rb 2 TcCl 6 is an attractive material for spintronic devices. A number of optical parameters are determined. For optoelectronic applications, Rb 2 TcCl 6 is an excellent choice due to its strong polarization in the visible and ultraviolet regions, as shown by its optical characteristics. [ABSTRACT FROM AUTHOR]

Rare-earth zirconate pyrochlores (RE2Zr2O7) are of much fundamental and technological interest as optoelectronic, scintillator and thermal barrier coating materials. For the first time, we report the detailed optoelectronic properties of rare-earth zirconates Nd2Zr2O7 in both, i.e., for spin up and spin down states, via the use of first-principles density functional theory (DFT) procedure. To obtain the desired optoelectronic properties, we used a highly accurate method called full-potential linearized augmented plane wave (FPLAPW) within the generalized gradient approximation (GGA), parametrized with Hubbard potential U as an exchange-correlation function. The band gaps predicted for Nd2Zr2O7 were of the order 2.4 eV and 2.5 eV in Fd-3m and Pmma symmetrical phases, respectively. For both the phases, our research involved a complete examination of the optical properties of Nd2Zr2O7, including extinction coefficient, absorption coefficient, energy loss, function, reflectivity, refractive index, and real optical conductivity, analyzed in the spectral range from 0.0 eV to 14 eV. The calculated optical properties in both phases showed a considerable spin-dependent effect. The electronic bonding characteristics of different species in Nd2Zr2O7 within the two crystal symmetries were explored via the density distribution mapping of charge. [ABSTRACT FROM AUTHOR]

This study reports the intriguing properties of a novel ternary silver-based sulfo-spinel vanadium system (AgV2S4) having a face centered cubic structure (FCC). The magnetic nature, electronic behavior and optical properties of this system are revealed. The calculations were performed with spin-effect and by using generalized gradient approximation (GGA) under Density Functional Theory (DFT). After obtaining the optimized Wyckoff positions for the atoms in the crystal structure of this composition, it was decided that this spinel material has ferromagnetic nature in view of the energy-volume curves obtained for three different magnetic phases and of the calculated cohesive energies. Furthermore, the spin-polarized electronic band structure with the orbital projected density of electronic states was calculated within the first principles to investigate its behavior and bonding characteristic in detail. The observed small band gap in the minority spin channel is Eg = 0.41 eV, so its electronic band structure implies that this system has half-metallic character. Finally, to evaluate some optical features, frequency-dependent complex dielectric functions were calculated. Then, some optical properties were investigated by using the real and [ABSTRACT FROM AUTHOR]

This paper explains our first-principle computational investigation regarding the structural, optical, elastic, and electrical characteristics of gallium-based GaMF3 (M = Be and Ge) perovskite-type (halide-perovskite) compounds. Our current computation is based on density functional theory (DFT) and is achieved with the help of the WIEN2k code. We used the Birch–Murnaghan equation for optimization; in both compounds, we found that both GaBeF3 and GaGeF3 compounds are structurally stable. For the computation of elastic characteristics, the IRelast package for calculating elastic constants (ECs) is utilized. These compounds are mechanically ductile, scratch-resistant, anisotropic, and mechanically stable, showing huge opposition to plastic strain. The modified Becke–Johnson (TB-mBJ) potential approximation method is used to calculate different physical characteristics and shows that GaGeF3 behaves as a metal, whereas the GaBeF3 compound is insulating in nature. The involvement of various electronic states in band structures is calculated using the theory of the density of states. The different optical properties of these compounds can be studied easily using their band gap energy. At high energy ranges, these substances demonstrate strong absorption. At low energies, the GaGeF3 compound is transparent, while the GaBeF3 compound is opaque to incoming photons. Investigation of the optical characteristics has led us to the conclusion that both GaGeF3 and GaBeF3 compounds can be used for high-frequency ultraviolet device applications. This computational work is considered to be the first time that we can study these compounds, which to our knowledge have not previously been experimentally validated. [ABSTRACT FROM AUTHOR]

Using first principles calculations employing density functional theory (DFT) we have investigated the electronic properties of Si 2 BN nanotubes having 10 Å and 15 Å (armchair and zigzag) diameters. The obtained electronic band structures reveal all structures to be metallic in nature. The partial density of states (DOS) shows that the contributions of 3p state of Si is most prominent in the conduction band and majority contribution of the valence band is due to the 2p state of N atoms for all nanotubes. H 2 storage in Pd doped Si 2 BN nanotubes (Si 2 BN@Pd) was investigated up to the maximum limit. Our calculations have uncovered the possibility of storing 2H 2 and 3H 2, respectively, inside, and outside of the Si 2 BN@Pd in each unit cell. When diameter increases from 10 Å to 15 Å the static dielectric constant, ε 1 (0), upsurges in value from 6.9 to 10.7. The variation in n(ω) for the 10 Å diameter nanotube, with and without H 2 molecules, indicates no significant changes after the sensing of H 2 molecules, while in the 15 Å diameter nanotube, the n(0) value in the near infra-red (NIR) region is found to decrease and shows a further decrease if we store more H 2. We have also calculated the adsorption energies for the Si 2 BN@Pd and Si 2 BN@PdH 2 structures (for 10 Å and 15 Å diameters). Our theoretical approach has revealed that the Si 2 BN nanotube can efficiently store hydrogen and we propose efficient ways for hydrogen storage for future improvements. [Display omitted] • Si 2 BN nanotubes doped with palladium (Pd) atom are promising candidates for H 2 storage. • The admirable cohesive energy of the nanotubes is used to get high dynamical stability of the structures. • Adsorptions of hydrogen molecules on pristine Si 2 BN nanotubes are improved by Pd doping. • The optical properties of H 2 absorbed Si 2 BN@Pd nanotubes are systematically investigated. [ABSTRACT FROM AUTHOR]

The electronic, optical and mechanical properties of AlCu:XO 2 alloys (X=Hf, Zr) are investigated for the first time through the Density Functional Theory (DFT). The aim of this work is to evaluate the impact of aluminum-copper alloys on the physical response of high-k materials for both electronic and photocatalysis devices applications. It will be shown that 25% of Al is the appropriate composition leading to improved electrical and optical properties. Whereas by increasing the AlCu content (25%), the band gap energy decreases to reach 2.96 and 2.37 eV for HfO 2 and ZrO 2 respectively. A shift of the optical absorption to the visible light region is also observed making these configurations adequate for photocatalytic devices applications. The presence of AlCu alloy in these oxides shows that it is possible to reduce or suppress the defect states according to the electronic structure and enhance the mechanical stability of the AlCu:XO 2 alloys. • The Electronic properties of AlCu-XO2 (X=Hf and Zr) is studied through the Density Functional Theory. • The field of application depends on the Al-Cu content. • The presence of the Al-Cu alloys reduces or suppresses the defect level within the valence band. • The mechanical stability of the AlCu-XO 2 structures is discussed with respect to the Al-Cu concentration. [ABSTRACT FROM AUTHOR]

Double perovskite (DP) structures have attracted considerable interest because of their possible utilization in optoelectronic and thermoelectric equipment. This study employs the GGA for structural and Tran–Blaha modified Becke–Johnson exchange potential approximation (TB-mBJ) for electronic and optical and IRelast to investigate the elastic properties within the Wein2k software of Cs 2 ScCuCl 6 and Cs 2 ScCuF 6 compounds. The compounds under consideration are determined to be structurally stable. Elastic properties demonstrate that both compounds exhibit elastic stability, ductility, and anisotropy. Analysis of the electronic band structure indicates that Cs 2 ScCuCl 6 and Cs 2 ScCuF 6 are semiconductors with indirect band gaps of 1.2 eV and 1.8 eV, respectively, at symmetrical points along the (X-X) direction. The study also delves into the optical characteristics, discussing the real and imaginary parts of the dielectric function, refractive index, reflectivity, optical conductivity, absorption coefficient, and extinction coefficient regarding optical spectra. The findings suggest potential uses for these materials in semiconductor industries and modern electronic devices due to their efficient properties. Our finding may add comprehensive insight to invoke experimentalists for further investigations employing applications in light-emitting diodes (LEDs), photo-detectors, or solar cells. • This study in Wien2k analyzes Cs2ScCuCl6 and Cs2ScCuF6 using GGA for structure, TB-mBJ for electronic and optical properties, and IRelast for elastic properties. • The compounds under consideration are determined to be structurally stable. Elastic properties demonstrate that both compounds exhibit elastic stability, ductility, and anisotropy. • Analysis of the electronic band structure indicates that Cs 2 ScCuCl 6 and Cs 2 ScCuF 6 are semiconductors with indirect band gaps of 1.2 eV and 1.8 eV, respectively, at symmetrical points along the (X-X) direction. • The study examines various optical traits in spectra. [ABSTRACT FROM AUTHOR]

The demand for sustainable semiconducting devices that can be used in various applications necessitates the development of revolutionary materials with multifunctional properties. Using van der Waals interactions corrected first-principles density functional theory (DFT) calculations, we propose porous g-XO (X = Ge, Cu) inorganic graphenylene monolayers. These monolayers extend the family of synthesized porous organic graphenylene materials. Stability checks reveal that the g-XO monolayers are energetically, mechanically, dynamically, and thermally stable. Additionally, g-GeO monolayer is auxetic 2D material. The auxetic property of g-GeO monolayer could be advantageous for important applications in mechanics and tissue engineering, electromechanical devices, and flexible electronics. Based on the HSE06 electronic band structure results, these g-CuO and g-GeO monolayers exhibit wide and ultra-wide indirect bandgap semiconducting properties, respectively. The satisfactory absorption coefficient of 10 4 –10 5 cm−1 spanning the visible to UV region implies their potential for optoelectronics and UV shields applications. Our theoretical results provide a hints for the potential of these porous g-XO monolayers in energy harvesting/conversion, nanofiltration membranes, optoelectronic, thermoelectric, and flexible electronics. [Display omitted] • The porous g-XO (X = Ge, Cu) monolayers have been investigated using DFT calculations. • g-XO monolayers are energetically, mechanically, dynamically, and thermally stable. • g-GeO monolayer is auxetic 2D material. [ABSTRACT FROM AUTHOR]

CdTe1-xSex (CTS, x ≈ 0.1) thin film was prepared by quasi close-space sublimation method. The phase analysis and crystal structure refinement was examined with using X-ray diffraction data. CTS thin film crystallizes in cubic structure (structure type—ZnS, space group F-43 m, with unit-cell constants a = 6.395(3) Å and V = 261.6(4) Å3). Chemical composition of the films was examined using energy-dispersive spectroscopy (EDS). The estimated optical bandgap value of CTS (x ≈ 0.1) equal to ~ 1.37 eV. The electronic band structure of the CTS solid-state solution in the framework of the density functional theory calculations is investigated. The structures of the samples are constructed on the original binary compound CdTe, which crystallizes in the cubic phase. Based on the electronic band structure, the effective mass of electron, heavy hole, light hole, spin–orbit effective masses and reduced mass in G point are calculated. In addition, the exciton-binding energy, refractive index and high-frequency dielectric constant are calculated. [ABSTRACT FROM AUTHOR]

Structural parameters, electronic and optical properties of triphenylene have been investigated using the plane-wave ultrasoft pseudopotential technique based on the first principles density functional theory. The pressure dependence of the electronic band structure, density of states and partial density of states of triphenylene were presented. Meanwhile, the complex dielectric function, refractive index, absorption coefficient, reflectivity, and the extinction coefficient are calculated and analysed. According to our work, we found that the optical properties of triphenylene undergo a red shift with increasing pressure. [ABSTRACT FROM AUTHOR]

In the present work, we have investigated the structural, electronic and optical features of ZnS1−xOx graphene-like monolayer's for different x values compositions (0, 0.25, 0.5, 0.75 and 1) using the modified Becke–Johnson approach calculations within the framework of the density functional theory (DFT). The lattice parameter has been determined and found to deviate from Vegard's law for the ZnS1−xOx monolayer. The electronic band structure has been explored where the band gap energy has been found to be non-zero and direct in nature. This makes our material useful for optoelectronic devices. Besides, the optical spectra of the real and imaginary parts of the dielectric function along with the refractive index have all been addressed and found to be in good accordance with previous works reported for ZnS and ZnO monolayer's. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (hBN) has attracted a lot of attention in the past years, thanks to its many remarkable properties. These include the presence of single‐photon emitters with superior optical properties, which make it an ideal candidate for a plethora of photonic technologies. However, despite the large number of experimental results and theoretical calculations, the structure of the defects responsible for the observed emission is still under debate. In this work, individual atomic‐scale defects in hBN with atomic force microscopy under ambient conditions are visualized and multiple narrow emission lines from optically stable emitters are observed. This direct observation of the structure of the defects combined with density functional theory calculations of their band structures and electronic properties allows associating the existence of several single‐photon transitions to the observed defects. The work sheds light on the origin of single‐photon emission in hBN that is important for the understanding and tunability of high‐quality emitters in optoelectronics and quantum technologies. [ABSTRACT FROM AUTHOR]

Rare-earth zirconate pyrochlores (RE2Zr2O7) are of much fundamental and technological interest as optoelectronic, scintillator and thermal barrier coating materials. For the first time, we report the detailed optoelectronic properties of rare-earth zirconates Nd2Zr2O7 in both, i.e., for spin up and spin down states, via the use of first-principles density functional theory (DFT) procedure. To obtain the desired optoelectronic properties, we used a highly accurate method called full-potential linearized augmented plane wave (FPLAPW) within the generalized gradient approximation (GGA), parametrized with Hubbard potential U as an exchange-correlation function. The band gaps predicted for Nd2Zr2O7 were of the order 2.4 eV and 2.5 eV in Fd-3m and Pmma symmetrical phases, respectively. For both the phases, our research involved a complete examination of the optical properties of Nd2Zr2O7, including extinction coefficient, absorption coefficient, energy loss, function, reflectivity, refractive index, and real optical conductivity, analyzed in the spectral range from 0.0 eV to 14 eV. The calculated optical properties in both phases showed a considerable spin-dependent effect. The electronic bonding characteristics of different species in Nd2Zr2O7 within the two crystal symmetries were explored via the density distribution mapping of charge.

In this study, the ground state physical properties of Hg-based chalcopyrite semiconductors, HgXN 2 (X = Si, Ge and Sn), are investigated using the density functional theory (DFT), which is based on full potential linearized augmented plane wave (FP-LAPW) method. The structural, electronic, optical, mechanical and thermal properties of the body-centered tetragonal (BTC) phase, HgXN 2 (X = Si, Ge and Sn), have been calculated using the modified Becke-Johnson exchange-correlation potential (TB-mBJ). The obtained lattice parameters and volume are in good agreement with the values reported earlier, indicating that the results are reliable and reproducible. The phase stability of the titled compounds is elaborately studied and it is confirmed that all are thermodynamically, dynamically and mechanically stable. The electronic band structure demonstrated a direct band gap of 1.70 eV, 0.99 eV, and 0.94 eV for the HgXN 2 (X = Si, Ge and Sn) compounds, respectively. Both HgGeN 2 and HgSnN 2 compounds have a notably lighter carrier effective mass, resulting in higher carrier mobility and conductivity than HgSiN 2. The order of the mechanical hardness is as follows: HgSiN 2 > HgGeN 2 > HgSnN 2. The studied materials are also anisotropic in mechanically and optically. All the title compounds exhibit ductile behavior. The charge density contour plots indicates the dominant covalent nature of the bonds in HgXN 2 (X = Si, Ge and Sn). All these compounds have a high absorption coefficient and low optical reflectivity in the visible light range. Due to the favorable band gap and high absorption coefficient, these compounds could be suitable for optoelectronic or photovoltaic device applications. Moreover, the thermal expansion coefficient, thermal conductivity, melting point and fracture toughness behavior have been calculated, which also showed promise for thermal barrier coating (TBC) applications. • A comprehensive theoretical study on HgXN 2 (X = Si, Ge and Sn) compounds using DFT calculations. • The compounds are thermodynamically, dynamically and mechanically stable. • The compounds are ductile and elastically and optically anisotropic in nature. • The electronic band gap is 1.70, 0.99, and 0.94 eV for the HgXN 2 (X = Si, Ge and Sn) compounds, respectively. • The compounds can be used as potential coating materials in some specific sectors. [ABSTRACT FROM AUTHOR]

• First-principles investigation of the structural, phonon, elastic, electronic, thermoelectric, optical and photocatalytic properties of double perovskites Cs 2 BB'H 6 (B = Al, Na and B'=Tl, In) is done. • The optimization cures, negative formation energy and positive phonon curves show the stability of the studied compounds. • The electronic band structure and density of states (DOS) reveals the semiconductor nature of both compound. • An optical band gap with maximum absorption reveals that this compound is also useful for the application in optoelectronics. • The thermoelectric response suggests their availability for thermoelectric devices. • Photocatalytic properties show the excellent response of both compounds for solar hydrogen synthesis. Double perovskites Cs 2 BB'H 6 (B = Al, Na and B'=Tl, In) have been scrutinized by employing density functional theory to calculate their electronic structures, thermodynamic stability, elastic, optical, thermoelectric and photocatalytic properties. The FP-LAPW is utilized in the WIEN2k code for the calculations. Exchange correlation potentials such as modified Becke-Johnson with the addition of spin-orbital coupling are employed. The positive phonon frequencies, negative formation energies and optimization curves of the structures endorse the complete stability of studied perovskites. Mechanical properties also provide evidence of the structure's stability. Both compounds exhibit a semiconductor nature with an indirect bandgap of 2.38 eV and 2.51 eV for Cs 2 AlTlH 6 and 3.34 eV and 3.40 eV for Cs 2 NaInH 6 with mBJ and mBJ+SOC potentials, respectively. The partial and total densities of states have been computed to investigate the orbital's contribution. Calculations for optical response show the lowest energy loss and highest absorption in the ultraviolet range validating their use in optoelectronic devices. In addition, the evaluated thermoelectric response reveals their strong potential to use in renewable energy applications. Photocatalytic properties show the excellent response of both compounds for solar hydrogen synthesis. [ABSTRACT FROM AUTHOR]

Organic-inorganic perovskite materials have attracted significant attention in solar technologies due to their extraordinary structural, electrical, and optical features. This study extensively examined the impacts of bidirectional tensile and compressive strains and spin-orbit coupling (SOC) on the structural, electronic and optical characteristics of formamidinium lead iodide perovskite (FAPbI 3) structures. The investigation was performed using the first-principles density-functional theory (DFT). The electronic band structures of FAPbI 3 without SOC revealed that the perovskite structure possesses the characteristics of a semiconductor, explicitly featuring a direct bandgap. The application of compressive strains resulted in dwindling the electronic bandgap while tensile strains upsurged the bandgaps, except at +6 % strains. The incorporation of the SOC subjugated a notable decrease in the bandgap, causing a transition of the perovskite structure from a direct bandgap to an indirect bandgap state. The real dielectric constant suggested that the system maintains its semiconducting character under the exposure of both compressive and tensile strains. The imaginary part of the dielectric function, loss spectrum, and absorption coefficient peaks of FAPbI 3 perovskites exhibited a blueshift when subjected to compressive strains. However, the application of tensile strains eventuated in a redshift. The electronic and optical characteristics indicated that FAPbI 3 perovskites have great potential for optoelectronic devices, including LEDs, LCD backlights, solar cells, lasers, and light detectors. [Display omitted] • Cubic FAPbI 3 perovskite exhibits a direct bandgap semiconducting nature. • Compressive and tensile strains reduce and increase bandgaps, respectively. • SOC causes the perovskite from a direct bandgap to an indirect bandgap one. • Compressive and tensile strains result to blueshift and redshift, respectively. • All strains maintain semiconducting behavior of FAPbI 3 perovskite structure. [ABSTRACT FROM AUTHOR]

Experimental and Density Functional Theory (DFT) studies on the structural, magnetic and optical properties of rare-earth orthoferrites RFeO 3 (R = La, Pr, Nd, and Sm) were performed. The synthesis was carried out via the Ethylenediaminetetraacetic acid (EDTA)-citrate method. All these perovskites exhibited orthorhombic crystal structures with a space group Pbnm , and their lattice parameters and unit cell volumes decreased as a function of the rare earth ionic radius, as it was expected. The microstructural analysis indicates that all the perovskites share similar textural properties. The magnetic characterization revealed a weak ferromagnetic behavior attributed to the canted antiferromagnetic Fe3+ sublattices, with the dominant magnetic configuration identified as the G-type. Super-exchange interactions between Fe3+-O-Fe3+, R3+-O-Fe3+, and R3+-O-R3+ couplings facilitated a long-range magnetic ordering. The optical characterization indicated d - d electronic transitions, and the perovskites were confirmed as semiconductors with a bandgap of approximately 2.1 eV. The calculation of the transition dipole moment demonstrates two significant aspects: the electronic transition is direct and allowed, and its enhancement is evident in the Sm sample. Overall, this study provides valuable insights into the crystal structure, magnetic properties and optical behavior of RFeO 3 perovskites, synthesized via the EDTA-citrate method. • RFeO 3 (R = La, Pr, Nd, and Sm) perovskites have been successfully synthesized via the EDTA-citrate method. • The obtained materials exhibited a weak ferromagnetism arising from canted Fe3+ sublattices. • At room and low temperatures, M - H curves shows an exchange bias effect. • The calculation of the transition dipole moment demonstrated a direct allowed electronic transition. • DFT analysis identified a prevailing G-type magnetic configuration that promotes a long-range order. [ABSTRACT FROM AUTHOR]

We report on our results obtained on the physical properties of BxInyGa 1 − x − y N quaternary alloys in the zinc-blende phase that are thoroughly considered by the linearized augmented plane wave method, with a full potential within density functional theory, for different concentrations x and y as employed in the Wien2k code. We calculated the structural properties, including lattice constant a 0 and the bulk modulus B. We computed as well the band structures, the dielectric constant and the refractive index of our quaternary alloys compounds. Finally, nonlinear dependence on the compositions x and y are investigated in-depth and still expecting for experimental confirmations. To the best of our knowledge, this is the first theoretical investigation of BxInyGa 1 − x − y N alloy conducted to date. [ABSTRACT FROM AUTHOR]

The geometric, electronic and optical properties of SrCO3 under pressure up to 20 GPa are studied based on the density functional theory. The optimised structure parameters are in good agreement with the available experimental values. Meanwhile, the pressure dependence of the electronic band structure, density of states and partial density of states of SrCO3 were presented. It is shown that SrCO3 is an insulator with an indirect gap of 4.44 eV, and a pressure induced decrease of the band gap is observed. Moreover, the evolution of the dielectric function, absorption coefficient ( α (ω)), reflectivity ( R (ω)), and the real part of the refractive index ( n (ω)) at high pressure are also presented. According to our work, we found that the optical properties of SrCO3 undergo a red shift with increasing pressure. These results suggest technological applications of such materials in extreme environments. [ABSTRACT FROM AUTHOR]

Structural parameters, electronic and optical properties of biphenylene have been investigated using the plane-wave ultrasoft pseudo-potential technique based on the first-principles density functional theory. The non-uniform pressure dependence of the lattice parameters may also mean that the biphenylene undergoes anisotropic compression. And the bulk modulus at ambient pressure and temperature is B0 = 12.37 GPa and its derivative is B ′ 0 = 7.09. Meanwhile, the pressure dependence of the electronic band structure, density of states and partial density of states of biphenylene were presented. It is shown that biphenylene is a semiconductor with a direct gap of 2.325 eV, and a pressure induced decrease of the band gap is observed. Moreover, the complex dielectric function, absorption coefficient, reflectivity, refractive index and extinction coefficient are calculated and analysed. According to our work, we found that the optical properties of biphenylene undergo a red shift with increasing pressure. [ABSTRACT FROM AUTHOR]

We report first-principles studies the structural, electronic, and optical properties of the forsterite Mg2SiO4 in orthorhombic structure, including pressure dependence of structural parameters, band structures, density of states, and optical constants up to 30 GPa. The non-uniform pressure dependence of the lattice parameters may also mean that the forsterite Mg2SiO4 undergoes anisotropic compression. Meanwhile, the pressure dependence of the electronic band structure, density of states and partial density of states of forsterite Mg2SiO4 up to 30 GPa were presented. Moreover, the evolution of the dielectric function, absorption coefficient ( α (ω)), reflectivity ( R (ω)), and the real part of the refractive index ( n (ω)) at high pressure are also presented. According to our work, we found that the optical properties of forsterite Mg2SiO4 undergo a blue shift with increasing pressure. [ABSTRACT FROM AUTHOR]

In this work, electronic, optical and the magnetic properties of cubic ZnS doped with the transition metal (TM) Mn were numerically studied using the density functional theory code WIEN2K. The investigated concentrations included the compositional parameters x of 6.25%, 12.5% and 25% in Zn1-xMnxS. Computed electronic band structures and density of states (DOS) showed a half-metallic, ferromagnetic behavior with a direct band gap. The energy gap was found to increase with dopant concentration. Furthermore, optical properties such as the imaginary (ε2) and the real (ε1) part of the dielectric function, reflection, refractive index, absorption coefficient and optical conductivity show new transition peaks appear with Mn doping. The obtained results make the Zn1-xMnxS compound a promising candidate for spintronics devices. [ABSTRACT FROM AUTHOR]

In the present paper, we have investigated the electronic structure of some sillenites - Bi12MO20 (M = Ti, Ge, and Si) compounds based on the density functional theory. The mechanical and optical properties of Bi12MO20 have also been computed. The second-order elastic constants have been calculated, and the other related quantities have also been estimated in the present work. The band gap trend in Bi12MO20 can be understood from the nature of their electronic structures. The obtained electronic band structure for all Bi12MO20 compounds is semiconductor in nature. Similar to other oxides, there is a pronounced hybridization of electronic states between M-site cations and anions in Bi12MO20. Based on the obtained electronic structures, we further calculate the frequency-dependent dielectric function and other optical functions. [ABSTRACT FROM AUTHOR]

In this manuscript, the electronic structure, bonding nature and optical properties of the ternary Ba2HgS5 compound was investigated using the density functional theory (DFT). The generalised gradient approximation (GGA), Engel and Vosko generalised gradient approximation (EV-GGA) and the modified Becke Johnson (mBJ) schemes were used to model the exchange and correlation potentials. Band structure calculations indicate that this compound has a direct energy band gap value of 2.34 eV, showing a close agreement with the experimental band gap value of 2.40 eV. The energy band gap value calculated using the mBJ formalism is larger than those obtained from the GGA and the EV-GGA approaches. From the analysis of the partial electronic energy density of states, it was observed that the valence band is dominated by the Ba-p, S-s and Hg-d electronic states, while the conduction band is formed by the S-p and Ba-d orbitals. In addition, there exists a strong hybridisation in the valance band and in the conduction band between the S-p and Hg-s, Ba-s and Hg-f, Hg-s, S-p as well as the S-p and Hg-p states, respectively. This strong hybridisation leads to strong covalent bonding between the Hg-S and Ba-S atoms. Moreover, the optical constants were calculated and discussed in details. The energy dependent optical parameters were found to be anisotropic with respect to the polarisation of the incident electromagnetic wave and exhibit features in complete agreement with the electronic band structure calculations. The compound absorbs ultraviolet radiation quite strongly. Ba2HgS5 possesses high refractive index over a wide range of frequency and has potential to be used as anti-reflective coating and also in photonic devices like in light emitting diodes (LEDs). [ABSTRACT FROM AUTHOR]

A detailed theoretical study, based on density functional theory (DFT) with GGA-PBE, of electronic, optical and structural properties of calcium (Ca) and barium (Ba)-doped SrZrO3, is presented. The doping influence on the electronic structure and consequently optical properties are analysed and explained with TDOS and PDOS. Structural parameters vary by partial replacement of strontium (Sr) atom with Ca and Ba in SrZrO3, separately, and PDOS modify themselves with the development of new states at symmetry points and as a result reduction in the electronic band gap is observed. We have also noticed that the indirect band gap of pure SrZrO3 is altered to the direct band gap after doping. The optical properties of the pure and doped SrZrO3 are interrelated with their electronic determinations. The considerable change in the band structure and optical properties by doping of Ca and Ba assert that the doped material is a more attractive contestant for optoelectronic device applications as compared to pure SrZrO3. [ABSTRACT FROM AUTHOR]

In this study, the electronic and optical properties of wurtzite MgxZn1−xO structures for different Mg mole fractions (x) are studied using Density Functional Theory (DFT). In calculations, the generalised gradient approximation (GGA + U) formalism is used with the Hubbard parameters (U) are applied to Zn-3d and O-2p electrons of ZnO. The calculated electronic band structures show that the band gap energies of the investigated structures increase linearly with increasing Mg mole fraction from 0 to 31.25% which is also quantitatively consistent with the previous experimental results. In addition, the electron effective masses of investigated MgxZn1−xO structures are calculated. The electron effective masses of investigated structures show an increment linearly with increasing Mg mole fractions. The optical results show that the absorption edges of the structures move toward the higher energies region as the Mg mole fractions increase. [ABSTRACT FROM AUTHOR]

We performed ab initio calculations to study the structural and optoelectronic properties of simple and slab phase TaNO using density functional theory (DFT), in which the full potential augmented plane wave (FP-LAPW) method was implemented using the computational code Wien 2k. The modified Becke-Johnson potential (mBJ-GGA) was used for these calculations. The calculated band structure and electronic properties revealed an indirect bandgap for simple TaNO (3.2 eV) and a direct bandgap for slab TaNO (1.5 eV). The interband electronic transitions were investigated from the band structure, and transition peaks were observed from the imaginary part of the dielectric function. These transitions are due to Ta-p, N-p and O-p orbitals for simple TaNO and Ta-p, N-s as well as O-p orbitals for slab TaNO. The plasmon energy was related to the main peak of the energy loss function, which was approximately 10 eV. The static value of the dielectric constant and the refraction were close to the experimental values. In general, slab TaNO shows different properties and is more suitable for optoelectronic applications due to direct bandgap. Image 1 • DFT calculations of the structural and optoelectronic properties for bulk and slab phase TaNO. • The electronic properties reveals a direct (indirect) band gap for slab (simple) TaNO. • The interband electronic transitions are investigated by band structure. • Slab TaNO shows different properties and is more suitable for optoelectronic applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • KCaF 3 Fluoro-Perovskite has been investigated using Density Functional Theory (DFT). • Li-doping results in the reduction of band-gap. • KCaF 3 halide perovskite are found to be thermodynamically stable. • The electronic analysis showed that the studied compound is semiconductor. In order to evaluate the effects of Lithium (Li) doping on the various properties of KCaF 3 , we present first-principles calculations built on density functional theory (DFT) and employing approximation GGA-PBE. The compound possesses a 2 × 2 × 1 supercell and cubic geometry with space group pm3m. By putting the TDOS and PDOS concepts into practice, the effects of Li-doping on electronic structure and, consequently, optical characteristics have been investigated and evaluated in detail. With the formation of new states in band structure, the substitution of the Lithium (Li) atom for the Calcium (Ca) atom drastically adjusts the electronic band structure. The indirect bandgap of pure KCaF 3 was measured to be 5.37 eV. The band gap was slightly shrunk as a result of changes in Li concentration. This causes the indirect band gap of KCaF 3 to change to the direct band gap for Li-doped KCaF 3. A strong interaction between the Li atom and the atoms around it is seen and the density of states for Li-doped KCaF 3 relocates at slightly lower energies. Additionally, there is a noticeable change in the partial density of states of KCaF 3 near the conduction band bottom, leading us to believe that Li-doping has an impact on the electronic band structure. Investigations into the optical characteristics of doped and undoped KCaF 3 and correlations with its electrical structure are made. The massive difference in optical characteristics and band gap (i.e., indirect to direct) caused by Li-doping makes this substance a desirable candidate for optoelectronic materials. [ABSTRACT FROM AUTHOR]

In this article comprehensive study of the thermoelectric and optical properties of the Zn₀.₉₅Cd₀.₀₅X (X = S, Se and Te) by using first principle DFT calculation incorporating the Wien2k code, has been considered. Firstly, we determined the optimized structural parameters, comprising of the atomic coordinates. All the properties like the energy band structure, densities of electronic states and energy dependence of the optical functions were figured out. We found the decrease in their band gaps (3.5 eV, 3.0 eV and 1.9 eV respectively) as we replace S by Se and Te, respectively. We found that they are having direct band gap having transition along Γ- Γ symmetry point. The electronic interband transitions accountable in the optical spectra were specified. In parallel the standard Boltzmann transport theory were used to calculate the thermoelectric parameters, including Seebeck coefficient, electrical and thermal conductivities and figure of merit. In response we found that the investigated compounds are potential candidates for thermoelectric applications. [ABSTRACT FROM AUTHOR]

• Investigation of the structural, phonon, elastic, electronic, transport and optical properties of double perovskites K 2 TlAsX 6 (X = Cl, Br) is done by employing first-principles calculation. • The optimization cures, negative formation energy and positive phonon curves show the stability of the studied compounds. • The electronic band structure and density of states (DOS) reveals the semiconductor nature of both compound. • An optical band gap with maximum absorption reveals that these compounds are useful for the application in optoelectronics. • The thermoelectric response suggests their availability for thermoelectric devices. Double perovskites with their significance properties are considered to be promising candidates for an extensive range of applications. Current research work includes the theoretical analysis of the physical characteristics of K 2 TlAsX 6 (X = Cl, Br) double perovskites under the framework of DFT. The precise band structure calculations have been done using modified Becke-Johnson (mBJ) with the inclusion of spin–orbit coupling (SOC) effect. Negative formation energies, structural optimization, positive phonon frequencies and tolerance and octahedral factors support the stability of the perovskites. Elastic parameters, including anisotropic factor, Pugh's and Poisson's ratios, and Cauchy pressure, are calculated to quantify mechanical characteristics. A direct band gap is obtained in both perovskites possessing the values of 2.22 eV and 1.59 eV for K 2 TlAsCl 6 and 1.97 eV and 1.51 eV for K 2 TlAsBr 6 with mBJ and mBJ + SOC, respectively. The compound's optical response is scrutinized, showing the absorption in visible and UV regions. The transport characteristics are also evaluated, showing their high electrical conductivity and ZT values and simultaneously small thermal conductivity values for both perovskites. The optical and transport properties reveal the capacity of K 2 TlAsCl 6 and K 2 TlAsBr 6 to be used in optoelectronic and green energy applications. [ABSTRACT FROM AUTHOR]

In this work the Fritz-Haber Institute ab initio Molecular Simulation (FHI-aims) code was used to investigate and obtain the band energies and linear dielectric functions of the three naturally occurring phases of TiO2 (Rutile, Anatase and Brookite). The exchange-correlation interactions are treated by the PBE. The results of the band gap were obtained to be 1.76 eV for Rutile, 2.07 eV for Anatase and 2.33 eV for Brookite with Rutile having a direct band gap and indirect band gaps for both Anatase and Brookite. The obtained band gaps are in agreement with other theoretical work, especially on the rutile phase. The linear dielectric function was calculated using Random Phase Approximation (RPA) where the average static dielectric function at ω= 0 was obtained as 5.61 for Rutile TiO2, 4.29 for Anatase TiO2 and 2.23 for Brookite TiO2. [ABSTRACT FROM AUTHOR]

The electronic bandstructure, optical and structural properties of pure and Mg-doped CaTiO 3 are calculated by using first-principle calculation which is based on the density functional theory. The effect of Mg-dopant on the properties of CaTiO 3 perovskite explored by using ultra soft pseudo-potential (USP) and generalized gradient approximation (GGA). The incorporation of Mg at Ca site affected the electronic band structure of CaTiO 3 meaningfully by introducing new gamma point. The incorporation of Mg increases the band gap from 1.84 eV to 1.92 eV. The partial density of states of pure CaTiO 3 changed after doping cleared the effect of dopant on pure system. Optical properties of both the systems are examined which reveals that the absorption edge shifting from 2.1 eV to 2.5 eV indicates a blue shift whereas the refractive index also increases from 2 to 2.4 after doping. Thus Mg-doped CaTiO 3 not only affect the optical properties of the system but also make it and appealing candidate for optical devices. • Electronic and optical properties of Mg-doped CaTiO 3 are studied. • Mg-doped CaTiO 3 is remained the indirect band gap semiconductor but with.change of symmetry points. • Mg(d) state plays an important role in the doping system. [ABSTRACT FROM AUTHOR]

• Both SnI 2 and Sn 4 SI 6 have the layer crystal structure. • The crystal structure of Sn 4 SI 6 is equivalent to that of SnI 2 doped with S atoms. • The sulfur dopant atoms can affect the electronic band gap. • The positions of the optical peaks can be affected via doping by sulfur atoms. Layered luminescence semiconductors SnI 2 and Sn 4 SI 6 have been employed in electronic discharge lamps, photo-recording medium, and other applications, owing to their high color rendering index and high photosensitivity. The crystalline, electronic and optical properties of these two compounds were investigated by the density functional theory. The results indicate that the sulfur dopant atoms have a small effect on the profiles of the electronic band structure and optical curves. However, sulfur doping changes the electronic band gap, the positions of the absorption edge, and the dielectric and absorption peaks. These results support the further study and application of these two compounds. [ABSTRACT FROM AUTHOR]

In this paper we present the First-principles calculations, established on the density functional theory (DFT) by using generalized gradient approximation (GGA) and ultra-soft pseudo-potential (USP), study to investigate Magnesium (Mg) doping outcome on the different properties of SrZrO 3. The impacts on electronic structure and hence optical properties from Mg-doping have been explored and are reviewed in detail by implementing the conception of TDOS and PDOS. Replacement of Strontium (Sr) atom by Mg tunes the electronic band structure quite significantly with the emergence of new states at Gamma point. Due to this SrZrO3 indirect band gap is transformed to the direct one for Mg-doped SrZrO 3. The density of states for Mg-doped in SrZrO 3 relocate themselves at slightly lower energies and there is strong interaction between Mg-atom and its surrounding atoms is observed. Furthermore, at the conduction band bottom and partial density of states of SrZrO 3 change appreciably and hence we conclude that the electronic band structure is affected by Mg-doping. The optical properties of the un-doped and doped SrZrO 3 are investigated and are correlated with electronic structure. The enormous variation in optical properties and band gap (i.e indirect to direct) by doping of Mg declares this material as attractive contender for optoelectronic materials. [ABSTRACT FROM AUTHOR]

The photophysical properties of double perovskite oxides A 2 LuTaO 6 (ALT; A = Ba, Sr) are investigated to design new photovoltaic materials by exploring the photosensing and photocatalytic properties. The Raman spectra for Ba 2 LuTaO 6 (BLT) and Sr 2 LuTaO 6 (SLT) agree well with the room temperature crystal structures of the materials. The electronic band structure of BLT and SLT show a direct band gap at the Γ-point with the optical excitations occurring between the O p states and the Ta d states. The calculations reveal a comparable visible light absorption coefficient to other well-known ferroelectric perovskite solar cell candidates. In addition, an anisotropy is also developed in the optical properties as the symmetry gets reduced due to the prevalent octahedral distortions. The electrical charge transport, measured under both dark and illuminated conditions, is analyzed in terms of the thermionic emission theory of metal-semiconductor junction. The observed decrease in the Schottky diode resistance (R s) for all the materials can be correlated to the decrease in the potential barrier upon light illumination. The observed trends in photosensitivity are correlated to the changing symmetry and bond angles. The degradation of organic pollutant rhodamine-B (Rh-B) using BLT and SLT as photocatalysts are shown to possess relatively high degradation rates. The photodegradation kinetics is analysed in terms of the band gap, particle size, dielectric properties and structural changes. This work serves as a model to design new optoelectronic materials by correlating the theoretical electronic and optical properties to the experimentally observed optoelectronic and photocatalytic properties. [ABSTRACT FROM AUTHOR]