Context The new equations have been developed for the structural and electronic properties using the plasmon calculations for the first time for 2-D MoX 2 structures. Literature shows still an extensive study is required on the stability and optical properties of MoX2 under different hydrostatic pressures and thermal properties under different temperatures using the first principles, for electronic industrial applications. The stability is analyzed using binding energy and phonon calculations. The phase transition of metallization of MoX 2 is discussed using band structure calculations under different hydrostatic pressures. The calculated work function shows the photoemission starts from the threshold frequency of 4.189×10 4 cm -1 , 3.184×10 4 cm -1 , and 3.651×10 4 cm -1 , respectively, for MoS 2 , MoSe 2 , and MoTe 2 materials. The optical properties such as refractive index n(0), and static dielectric permittivity ε(0) for three successive materials are calculated under different hydrostatic pressures, applicable for optoelectronic applications. The calculated theoretical and computational values agree well with each other and also agree with reported and experimental values. Some of the values are calculated for the first time. Methods The theoretical equations are derived using the molecular weight, effective valence electrons, and density of molecule of MoX 2 structures. The simulation work is performed using GGA-PBE approximation in the CASTEP simulation package with DFT+D semi-empirical dispersion correction. An ultra-soft pseudopotential representation calculates the electronic and optical properties with a finite basis set kinetic energy cut-off of 381.0 eV. Each geometry has been optimized using Broyden, Fletcher, Goldfarb, and Shanno's (BFGS) algorithm for 100 iterations with a fixed basis quality variable cell method and finite electronic minimization parameters. The phonon calculations were performed using TDFT with a kinetic energy cut of 460 eV in a norm-conserving linear response method. The interpolation with a finite dispersion quality and q-vector grid spacing is performed.

The structural, electronic, and optical properties of transition metal dicalcogenide (WS2) semiconductors were calculated using DFT calculations. For the first time, the anisotropy and birefringence of WS2 are calculated in different energy regions. The estimated structural and electronic properties are in consider with the reported values.

In this paper, the physical properties of ZnGeN2 and GaN compound semiconductors are calculated under different pressures using the density functional theory calculations. The lattice parameters and energy bandgap are studied at ambient conditions. Further, the energy bandgap of ZnGeN2 and GaN under different pressures has been calculated. The bandgap values show that ZnGeN2 is a direct bandgap up to 100 GPa and becomes an indirect bandgap at 110 GPa. GaN is a direct bandgap up to 150 GPa and turns out to be an indirect bandgap semiconductor at 160 GPa. The elastic parameters, i.e., elastic stiffness coefficients, have been estimated in the range of 0−190 GPa pressures. Results show that ZnGeN2 and GaN are stable up to 180 and 150 GPa pressures, respectively. Comparative results show that the physical properties of ZnGeN2 have a resemblance with GaN up to 100 GPa pressure and can be a potential candidate in place of GaN in various technological applications.

The structural, electronic, and optical properties of fluorinated graphene under different hydrostatic pressures and thermodynamic properties under different temperatures have been studied using first-principle calculations. The calculated binding energy and phonon dispersion show that the fluorinated graphene is stable up to 90 GPa external pressure. The behavior of energy bandgap under different pressures shows that the electronic properties of fluorinated graphene are less pressure-sensitive compared to hydrogenated graphene. The functionalization increases the electron mobility of graphene. The fluorinated graphene is more temperature-sensitive compared to hydrogenated graphene and graphene. Six important parameters: energy bandgap (E-g), binding energy (E-b), dielectric constant epsilon(0), refractive index n(0), birefringence Delta n(0), conductivity threshold (sigma(th)) and plasmon energy (h omega(p)) have been reported under different pressures for the first time. The calculated values agree well with the available reported values at 0 GPa pressure.

The structural, electronic, and optical properties of hydrogenated silicene have been studied under different hydrostatic pressures using first-principle calculations. The binding energy and band structure have been calculated for chair (C-) and boat (B-) structures, which are having good stability at 0 GPa, 3 GPa, 6 GPa, 9 GPa, 12 GPa, 15 GPa, and 18 GPa hydrostatic pressures. Stability has been verified using binding energy and phonon calculations. The C- and B-structures have become metallic and unstable at 21 GPa. The optical properties of B-configuration have been studied in the energy range of 0–20 eV. Five optical parameters such as conductivity threshold (σ th ), dielectric constant ε(0), refractive index n(0), birefringence Δn(0), and plasmon energy (ħω p ) have been calculated for the first time under different hydrostatic pressures. The calculated values are in good agreement with the reported values at 0 GPa.

The structural, electronic, and optical properties of hydrofluorinated germanene have been studied with different occupancy ratios of fluorine and hydrogen. The hybridization of H-1 s and Ge-4p orbitals in hydrogenated germanene and F-2p and Ge-4p orbitals in fluorinated germanene plays a significant role in creating an energy bandgap. The binding energy and phonon calculations confirm the stability of hydrofluorinated germanene decreases with the increase of the F to H ratio. The value of the energy bandgap decreased by increasing the ratio of F and H. The optical properties have been studied in the energy range of 0–25 eV. Six essential parameters such as energy bandgap (E g ), binding energy (E b ), dielectric constant ε(0), refractive index n(0), plasmon energy (ћω p ), and heat capacity (C p ) have been calculated for different occupancies of H and F in hydrofluorinated germanene for the first time. The calculated values of structural parameters agree well with the reported values.

Bismuth titanate nanostructure, Bi12TiO20, (BTO) belonging to sillenite family was synthesized by chemical route at the sintering temperature 800 °C for a period of 6 h. The crystalline phase of the materials was investigated by the X-ray diffraction method. The morphology and particle size of the BTO sample were determined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis, respectively. The SEM images displayed the bimodal structure, and average grain size was found to be in the range of 0.6–3.7 µm. TEM observation confirmed the nanocrystalline nature of the particle having size of 50 ± 20 nm. The value of dielectric constant and dielectric loss for Bi12TiO20 ceramic was found to be 8.29 × 103 and 3.27, respectively, at the temperature 468 K and frequency 100 Hz.

First-principle calculations are performed to study the structural, electronic, optical and thermodynamic properties of hydrogenated germanene (germanane) for most stable chair (C-), boat (B-) and tricycle (T-) structures. The band structure is studied under different hydrostatic pressures. The germanane shows metallic behavior at 30 GPa, 25 GPa and 12 GPa external pressures, respectively, for C-, B- and T-configurations. The calculated binding energy shows that germanane becomes unstable at 30 GPa, 25 GPa and 6 GPa for C-, B- and T-conformers, respectively. The thermodynamic properties of germanane are calculated in the temperature range of 5-1000 K and compared with germanene. The optical parameters such as dielectric constant, refractive index, birefringence, and plasmon energies (h omega(p)) have been calculated for the first time. The calculated values are in good agreement with the experimental and reported values.

The electronic and elastic properties of [Formula: see text] defect-chalcopyrite semiconductors have been studied using first-principle density functional theory (DFT) calculations. The lattice constants, energy band gap, elastic stiffness constants, bulk modulus, shear modulus, shear anisotropy factor, Young’s modulus, Debye temperature, Poisson’s ratio and B/G ratio have been computed. The values of elastic constants of 14 defect-chalcopyrites and Debye temperature for 18 compounds have been reported for the first time. The obtained results are in reasonable agreement with the experimental values in few cases where experiments are performed and reported values.

The structural, electronic, optical, and thermodynamic properties of hydrochlorinated Janus graphene (J-GN) have been studied using first-principle DFT calculations. The band structure and density of states have been discussed. The values of 16 parameters have been calculated for the most stable chair (C) structure of hydrochlorinated J-GN. Out of sixteen, 12 parameters such as static dielectric constant ε(0), refractive index n(0), birefringence Δn(0), threshold conductivity σ(ω), plasmon energy (ћωp), binding energy (Eb), cohesive energy (Ec), enthalpy (E), entropy (S), free energy (F), heat capacity (Cp), and Debye temperature (ΘD) have been calculated for the first time. The structural and electronic properties have also been studied at 0-GPa, 25-GPa, 35-GPa, 50-GPa, 90-GPa, 100-GPa, 150-GPa, 200-GPa, and 220-GPa external pressures. The hydrochlorinated J-GN shows the direct band gap behavior up to 35 GPa and becomes indirect band gap after 35 GPa. Further, it shows a stable structure up to 90 GPa and becomes unstable at 100-GPa external pressure. The calculated values of all parameters agree well with the available reported values of some parameters at 0 GPa.

First principle calculations have been performed to study the structural, electronic, optical and thermodynamical properties of hydrofluorinated graphene. The band structure and density of states have been discussed. The optical properties have been described in parallel and perpendicular polarizations of electric field in the energy range of 0-25 eV. Thermodynamic properties have been calculated in the temperature range of 5 K-1000 K and compared with the graphene and hydrogenated graphene. The values of 16 parameters have been calculated, out of which 6 parameters such as static dielectric constant epsilon(0), refractive index n(0), birefringence Delta n(0), conductivity threshold of sigma(omega), plasmon energy (h omega(p)) and Debye temperature (Theta(D)) are calculated for the first time. The obtained results shows direct band gap nature of hydrofluorinated graphene fill 400 GPa and stable up to 150 GPa external pressure. The calculated values of all parameters agree well with the available data at 0 GPa.

First-principle calculations are performed to study the structural, electronic, and optical properties of chair-structured hydrogenated graphene (C-graphane) under different hydrostatic pressures. The lattice constants, bond lengths, bond angles, energy band gap, and binding energy are calculated in the pressure range of 0–300 GPa. The results show that C-graphane is stable up to 250 GPa but becomes unstable at 300 GPa, with direct band gap behavior up to 30 GPa but an indirect band gap at 35 GPa. The optical properties such as the static dielectric constant ε(0), refractive index n(0), birefringence ∆n(0), and plasmon energy (ћωp) are studied at different hydrostatic pressures of 0 GPa, 15 GPa, and 30 GPa for the first time. The calculated values of all the parameters are in reasonable agreement with available experimental and reported values.

First-principles calculations were performed, and the results from the study of structural, electronic and elastic properties of zincblende III-arsenide binary compounds (BAs, AlAs, GaAs and InAs) are presented. These properties have been calculated using an ab initio pseudopotential method based on density functional theory (DFT) with the local density approximation (LDA) for the exchange-correlation potential. The results obtained for the calculated properties have been compared with experimental data and other computational works. It has also been found that our results with LDA are in good agreement with other computational work wherever these are available.

The plane wave pseudo-potential method within density functional theory has been used to calculate the structural and elastic properties of AIBIIIC 2 VI semiconductors. The electronic band structure, density of states, lattice constants (a and c), internal parameter (u), tetragonal distortion (η), energy gap (Eg), and bond lengths of the A–C (dAC) and B–C (dBC) bonds in AIBIIIC 2 VI semiconductors have been calculated. The values of elastic constants (Cij), bulk modulus (B), shear modulus (G), Young’s modulus (Y), Poisson’s ratio (υ), Zener anisotropy factor (A), Debye temperature (ϴD) and G/B ratio have also been calculated. The values of all 15 parameters of CuTlS2 and CuTlSe2 compounds, and 8 parameters of 20 compounds of AIBIIIC 2 VI family, except AgInS2 and AgInSe2, have been calculated for the first time. Reasonably good agreement has been obtained between the calculated, reported and available experimental values.

Electronic band structure, density of state and lattice constants of LiInTe2 semiconductor have been calculated using first-principle density functional theory (DFT). Elastics stiffness constants, bulk modulus, shear modulus, Poisson's ratio and B/G ratio have been determined under 0 GPa, 2 GPa, 4 GPa, 5 GPa and 6 GPa pressures and found to be stable upto 5 GPa. Computed results are in reasonable agreement with the available results.

The optical properties of graphene have been studied using first-principle density functional theory (DFT) calculations. The dielectric function, refractive index and birefringence in parallel and perpendicular polarization of electric field to the plane of graphene under 0 GPa, 5 GPa and 10 GPa pressures have been studied. The values of these parameters at 5 GPa and 10 GPa have been calculated for the first time. In parallel direction, the threshold energy is blue shifted towards the IR region, whereas in perpendicular direction, it is red shifted towards the UV region. The calculated values are in good agreement with the earlier reported values.

Using solid-state theory of plasma oscillations, simple relations are proposed for the calculation of the second-order nonlinear optical (NLO) tensor coefficients of LiXTe2 (X = Al, Ga, In) semiconductors. The values of bond lengths, energy gaps, dielectric constant, and NLO tensor coefficients of Li-Te and X-Te bonds and their total contribution to LiXTe2 compounds are calculated at zero frequency. The calculated results are in reasonable agreement with the known and reported results.

The first-principle calculations have been used to study the optical properties of hydrogenated graphene (graphane) in the perpendicular polarization of electric field. The static dielectric constant, refractive index, birefringence and plasmon energies have been calculated for the first time.

First-principle calculations are performed to calculate the values of dielectric constant, refractive index, and energy-loss spectra for LiInTe2 semiconductor at different pressures. The calculated values are compared with available experimental and reported values. A fairly good agreement has been obtained between them.

Based on plasma oscillations theory of solids, simple relations have been proposed for the calculation of bond length, specific gravity, homopolar energy gap, heteropolar energy gap, average energy gap, crystal ionicity, bulk modulus, electronic polarizability and dielectric constant of rare earth divalent R+2X and trivalent R+3X monochalcogenides. The specific gravity of nine R+2X, twenty R+3X, and bulk modulus of twenty R+3X monochalcogenides have been calculated for the first time. The calculated values of all parameters are compared with the available experimental and the reported values. A fairly good agreement has been obtained between them. The average percentage deviation of two parameters: bulk modulus and electronic polarizability for which experimental data are known, have also been calculated and found to be better than the earlier correlations.