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The structural, elastic, electronic, and thermodynamic properties of a LiScSi1−xCx alloy in the α-phase were investigated using density functional theory with the plane-wave pseudopotential method and the alchemical mixing approximation in ABINIT code. We computed ground-state properties including lattice constants, bulk modulus, energy gap, refractive index, and optical dielectric constant for the LiScSi1−xCx compounds. Our results align well with existing theoretical data for the parent compounds LiScSi and LiScC. We found that the fundamental bandgap for the α-LiScSi1−xCx alloy varied from 0.865 eV to 1.143 eV using the B3LYP approach, indicating potential applications in optoelectronic devices such as photodetectors and light-emitting diodes (LEDs), where precise control over electronic and optical properties is crucial. Additionally, we calculated the electron and hole effective masses, which showed a decrease with increasing carbon concentration; the electron effective mass ranged from 0.042m* for LiScSi to 0.035m* for LiSiC. The LiScSi1−xCx alloy in the α-phase consistently exhibited direct semiconductor behavior (X → X) across all concentrations. We also predicted the variation in thermodynamic properties, including unit cell volume, bulk modulus, heat capacity, and thermal expansion coefficient, with temperature for various carbon concentrations. These findings contribute to a deeper understanding of the material's potential applications in electronic and thermoelectric devices. [ABSTRACT FROM AUTHOR]

The effect of compressive strain and tensile strain on the band structure and optical spectra of two-dimensional monolayer GaN has been investigated. Computations were performed within density functional-theory. The results show that tensile two-dimensional monolayer-GaN undergoes an indirect-to-direct transition, which makes the material suitable for light-emitting and laser diodes. The material of interest is found to exhibit different optical properties dependent on the strain. Besides, the absorption band becomes wider and the optical absorption coefficient is reduced negligibly by strain, making two-dimensional-GaN a good candidate for application in photovoltaics and flexible optoelectronics. • The effect of strain on band structure and optical spectra of 2D-GaN is addressed. • The tensile 2D-GaN material undergoes an indirect-to-direct transition. • The 2D-GaN exhibit different and novel fascinating optical properties by strains. • The optical absorption coefficient is deteriorated negligibly by strain. • 2D-GaN is found to be a good candidate for optoelectronics applications. [ABSTRACT FROM AUTHOR]

The present paper aims to investigate the structural, elastic, thermodynamic, electronic, and optical properties of CaMg 2 AN 3 ( A = Al and Ga) using first-principle calculations and quasi-harmonic Debye model. The obtained ground-state lattice parameters were in good agreement with the experimental values. Pressure effect on the structural parameters was tested up to 20 GPa, the results reveal that the contractions are higher along the c-axis than along the a-axis. The computed single-crystal elastic moduli show that the unidirectional constant C 11 is about 60% greater than C 33 . Cauchy pressure and Poisson ratio suggest that the chemical bonding in CaMg 2 AN 3 is a mixture of covalent and ionic characters. Elastic anisotropy was discussed using different approaches, and the results show a weak elastic anisotropy. By means of Gibbs program, we have evaluated the thermodynamic properties such as Debye temperature θ D , heat capacities C v and C p , and expansion thermal coefficient under pressure ranging from 0 to 20 GPa and at temperature ranging from 0 to 1500 K for both compounds. The evaluated value of Dulong–Petit limit of both the semiconductors is 360.5 Jmol - 1 K - 1 . Band structure curves show a direct band gap of about 1.88 and 0.78 eV for CaMg 2 AlN 3 and CaMg 2 GaN 3 , respectively. Density of states and charge densities analysis confirm the predicted ionic-covalent bonding in both nitrides. Additionally, optical functions such as the refractive index, the reflectivity, and the absorption coefficient were calculated and discussed for two polarized radiations. [ABSTRACT FROM AUTHOR]

We report on ab-initio all electrons spin-polarised density-functional calculations for the band structure, optical spectra and magnetisation of bulk MnAs with NiAs-type lattice structure with emphasis on their dependence on pressure. The aim of this contribution is to show how the investigated properties behave upon compression. Our findings are compared when possible with those reported in the literature showing generally reasonable accordance. Our results indicate that the material under load exhibits a metallic character. The studied optical spectra show an anisotropic character between the x and z directions and are shifted downwards with raising pressure. The predicted static refractive index values depend on the direction, spin channel and pressure. The effect of the spin channel on the electronic and optical properties is found to be important. At zero pressure, MnAs reaches a total magnetic moment of the order of 5.69 μB per cell which decreases with raising pressure. The material of interest can be regarded as a good candidate for use in fabricating novel functional materials due to the spin degree of freedom. [ABSTRACT FROM AUTHOR]

The present paper reports on the hydrostatic pressure dependence of the direct and indirect energy band-gaps, refractive index, static and high-frequency dielectric constants, exciton banding energy and exciton Bohr radius for CdTe in the zinc-blende structure. The applied pressure is taken in the range 0–30 kbar. The calculations are performed using a pseudopotential approach. At zero pressure, our results show a good accord with experiment for most studied optical properties. Nevertheless, for exciton binding energy and Bohr radius the use of Adachi's expression [S. Adachi, Properties of Group-IV, III–V, and II VI Semiconductors, Wiley, Chichester, 2005] has given poor results as compared to experiment. In this respect, a modified Adachi's expression formula have been proposed and found to give meaningful accord with experiment. Upon compression up to 30 kbar, the material of interest is found to remain a direct (Г-Г) band-gap semiconductor. All optical features being studied here have shown a monotonic behavior under compression. The present study can be useful for infrared applications. [ABSTRACT FROM AUTHOR]

The composition dependence of direct and indirect band gap energies, anti-symmetric gap, valence band width, refractive index and high-frequency and static dielectric constants has been investigated for GaAs 1-x N x ternary semiconductor alloys with the zinc-blende crystal structure over the whole nitrogen concentration range (x from 0 to 1). The calculations are mainly based on the pseudopotential approach within the virtual crystal approximation. The variation of band-gaps versus nitrogen content show important bowing parameters. Trends in ionicity have been discussed in terms of the anti-symmetric gap. The alloy concentration dependence of the optical parameters of interest is found to be highly nonlinear. [ABSTRACT FROM AUTHOR]

We present first principles calculations of structural, electronic and optical properties of ZnS1−xOxin the zinc-blende phase. We employ the full potential linearized augmented plane wave method within the density functional theory in the generalized gradient approximation and Engel–Vosko generalized gradient approximation. Features such as the lattice constant, the bulk modulus and its pressure derivative are reported. The agreement between our calculated results and available experimental and theoretical data is generally good. Direct and indirect energy band gaps as a function of the oxygen composition in the material of interest are presented and discussed. The material under investigation is found to remain a direct band gap semiconductor over all the alloy composition range (0–1). Furthermore, the optical properties such as the dielectric function, the refractive index, the reflectivity and the electron loss energy have also been reported and analysed. [ABSTRACT FROM AUTHOR]

A pseudopotential scheme, which incorporates compositional disorder as an effective potential, is used so as to calculate the optical properties of Ga x In 1− x P ternary alloys in the zinc-blende structure. Generally, the agreement between our results and the existing data in the literature is reasonable. The composition dependence of the studied features showed a non-monotonic behaviour for most studied features. Reasons for these findings are discussed. Moreover, the effect of the compositional disorder on the features of interest has been examined and found to be important for the calculation of optical properties of Ga x In 1− x P. [ABSTRACT FROM AUTHOR]

Abstract: First-principles molecular dynamics simulation has been performed so as to investigate the optical and energy-loss spectra of ZnS. Features such as dielectric function, density of states, reflectivity, refractive index and energy-loss function have been studied. Furthermore, the influence of temperature on the optical properties of interest is reported and discussed. [Copyright &y& Elsevier]

The results of pseudopotential calculations of the band structure and related electronic and optical properties of quasi-binary (GaP)(ZnSe) crystals in the zinc blende structure are presented. Trends in bonding and ionicity are discussed in terms of electronic charge densities. Moreover, the composition dependence of the refractive index and dielectric constants are reported. The computed values are in reasonable agreement with experimental data. The results suggest that for a proper choice of the composition x, (GaP)(ZnSe) could provide more diverse opportunities to achieve the desired electronic and optical properties of the crystals which would improve the performances of devices fabricated on them. [ABSTRACT FROM AUTHOR]

Highlights: [•] Electronic and optical properties of AlAs x Sb1−x mixed crystals. [•] Nature of the chemical bond in AlAs x Sb1−x mixed crystals. [•] Materials for mid-infrared lasers applications. [ABSTRACT FROM AUTHOR]

Abstract: Theoretical investigations of the electronic, optical and elastic properties of cadmium and zinc chalcogenides in the zinc-blende structure are performed using a pseudopotential formalism. Our results are in reasonable agreement with the available experimental data. Polynomial expressions are obtained for the electron effective mass and the static dielectric constant as a function of the fundamental energy band-gap. Relations of elastic constants ratio to the ionicity are also examined and discussed. [Copyright &y& Elsevier]

Abstract: ZnSe and ZnS are the prototype II–VI semiconductors and their cubic phase, which occurs naturally as a mineral, has been called the zinc-blende structure. ZnSe has received particular attention as a blue-lasing material and tremendous experimental efforts have been made to fabricate a sustainable ZnSe blue laser. On the other hand, the ternary system is a good candidate for developing optoelectronic devices such as light emitting diodes (LEDs) or semiconductor lasers. It is also used as waveguides and confinement layers in laser diodes (LDs). In the present study, we have computed the electronic and optical properties of ZnSe, ZnS and using the local model pseudopotential method under the VCA. A central aim of this study is to present the electronic and optical properties of the materials of interest in the zinc-blende structure. [Copyright &y& Elsevier]

Abstract: Information on the energy band gaps, the lattice parameters and the lattice matching to available substrates is a prerequisite for many practical applications. A pseudopotential formalism within the virtual crystal approximation is used to the zinc-blende Al x Ga y In1−x−y N quaternary alloys lattice matched to GaN substrate to predict their energy band gaps and optical properties. The range of compositions for which the alloy is lattice-matched to GaN is determined. Very good agreement is obtained between the calculated values and the available experimental data. The compositional dependence of direct and indirect band gaps and dielectric constants has been investigated. The information derived from this study may be useful for ultraviolet optoelectronic applications. [Copyright &y& Elsevier]

Abstract: The band structure and optical properties of the CdSe x Te1−x ternary mixed crystals have been studied using the pseudopotential formalism under an improved virtual crystal approximation approach. Quantities such as, energy gaps, band-gap bowing parameters, electron effective mass and dielectric constants are calculated. Our results agree well with the available data in the literature. The composition dependence of all studied quantities has been expressed by quadratic polynomial forms. [Copyright &y& Elsevier]

Results of optical spectra and thermal properties of double perovskite Ba 2 LuTaO 6 compound material are reported using the full-potential linearized augmented plane wave method and the quasi-harmonic Debye model. Optical properties reveal that the transparent nature of the material under focus covers a broad range of solar spectrum including the infrared, visible and lower part of the ultraviolet ranges. The influence of temperature and pressure effects on volume unit cell, bulk modulus and heat capacity is examined and discussed. [ABSTRACT FROM AUTHOR]

Collective effects and some response characteristics such as piezoelectric stress and strain constants, Fröhlich coupling parameter, optical electronegativity and exciton properties of CdSe x Te 1-x common-cation ternary alloys have been investigated. The calculations are carried out using a pseudopotential approach under a modified virtual crystal approximation that takes into account the alloy disorder effect, combined with the Adachi model. Generally, a good accord is obtained between our results and those available in the literature. The composition dependence of the features of interest shows that the Fröhlich coupling parameter remains almost constant, the piezoelectric properties vary almost linearly and the optical properties exhibit a non-linear behavior. [ABSTRACT FROM AUTHOR]

In this paper we present optical and exciton properties of Zn x Cd 1-x S using a pseudopotential approach within an improved virtual crystal approximation which includes the alloy disorder effect. Features such as, refractive index, dielectric constants, exciton reduced mass, exciton binding energy and exciton Bohr radius have been investigated and their dependence on composition has been examined and discussed. All features of interest are found to vary monotonically and non-linearly with the Zn content. The results obtained in the present study may provide useful information for use of this alloy system in various device applications from visible to ultraviolet light. [ABSTRACT FROM AUTHOR]

Abstract The temperature dependence of the band gaps, refractive index, high-frequency and static dielectric constants and optical phonon frequencies in GaAs has been computed by using a pseudopotential approach. Our findings for all features of interest at given temperatures yielded values that agree with those previously reported. The variation of the features being studied here versus temperature showed a monotonic behavior. The transverse optical (TO) and longitudinal optical (LO) phonon frequencies are shifted towards low frequencies when the temperature is raised from 0 to 600 K. The change in the LO-TO splittings by raising temperature reflects the change in the ionicity character of the material under investigation. [ABSTRACT FROM AUTHOR]

The electronic band structure and optical properties of In x Al 1-x As y Sb 1-y quaternaries under conditions of lattice mismatching and lattice matching to InP substrate have been investigated using a pseudopotential approach under the virtual crystal approximation. The extent of the indirect (Г-X)-to-direct (Г-Г) band gap transition in In x Al 1-x As y Sb 1-y /InP is found to occur at x = 0.38 which agrees reasonably with the data reported in the literature. The lattice mismatch percentage in the range −5%–0% is found to have no effect on the nature of the fundamental band-gap in In 0.50 Al 0.50 As y Sb 1−y which remains a direct (Г-Г) band-gap semiconductor. Trends in bonding and ionicity are discussed in terms of the antisymmetric gap and valence band width. The dependence of the refractive index on both indium concentration x in In x Al 1−x As y Sb 1−y /InP and lattice mismatch percentage in In 0.50 Al 0.50 As y Sb 1-y has been examined. Our results showed that more opportunities can be provided for all features of interest by a proper choice of the concentrations x and y (0 ≤ x ≤ 0.52, 0.56 ≤ y ≤ 1) and/or the lattice mismatch percentage. [ABSTRACT FROM AUTHOR]

The dependence of the refractive index upon temperature in ZnSe 1-x S x has been investigated using a pseudopotential approach. Our findings are in very good accord with the available experimental and previous theoretical data. The composition dependence of the refractive index is found to be non-monotonous exhibiting a non-zero refractive index bowing parameters. The refractive index is shown to vary continuously and monotonically with raising temperature for each composition x. The temperature linear coefficient values of the refractive index have been reported and their dependence on S content has been examined. Besides, the refractive index bowing parameter and its dependence on temperature are presented and discussed. [ABSTRACT FROM AUTHOR]

The dependence on hydrostatic pressure of the electronic and optical properties of zinc-blende AlSb semiconducting material in the pressure range of 0–20 kbar has been reported using a pseudopotential approach. At zero pressure, our findings showed that the electron and heavy hole effective masses are 0.11 and 0.38 m 0 , respectively. Moreover, our results yielded values of 3.3289 and 11.08 for refractive index and high frequency dielectric constant, respectively. These results are found to be in good accord with experiment. Upon compression, all physical parameters of interest showed a monotonic behavior. The pressure-induced energy shifts for the optical transition related to band-gaps indicated that AlSb remains an indirect (Г-X) band-gap semiconductor at pressures from 0 to 20 kbar. The trend in all features of interest versus pressure has been presented and discussed. It is found that the lattice parameter is reduced from 0.61355 to 0.60705 nm when pressure is raised from 0 to 20 kbar. The present investigation may be useful for mid-infrared lasers applications, detectors and communication devices. [ABSTRACT FROM AUTHOR]

The present work deals with the study of the properties of a laser diode based on ZnSe/Zn 1− x Mg x Se quantum well at room temperature. A low magnesium composition ( x = 0.08) is considered to ensure exciton lasing and to reduce the ternary alloy fluctuations. Optical gain has been calculated. The influence of the carriers’ density and the quantum well width on the optical gain and its maximum value has been examined and discussed. Furthermore the emission wavelength is also determined as a function of the quantum well width. The information derived from this study shows that our system is of possible emission in the blue region of the electromagnetic spectrum. Besides, the maximum of the optical gain is enhanced by increasing both the carriers’ density and the quantum well width. It is also found that the emitted wavelength is shifted toward higher values as the quantum well width is increased. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we study the structural, electronic and optical properties of AgSbS2, using full-potential linearized augmented plane wave and the pseudopotential plane wave scheme in the frame of generalized gradient approximation. Features such as the lattice constant, bulk modulus and its pressure derivative are reported. Our results suggest a phase transition from AF-IIb phase to rocksalt (B1) phase under high pressure. The calculated band structure and density of states show that the material under load has an indirect energy band gap X→(LГ) for AF-IIb phase (semiconductor) and a negative band gap W→(ГX) for B1 phase (semimetal). The optical properties are analyzed and the origin of some peaks in the spectra is discussed. Besides, the dielectric function, refractive index and extinction coefficient for radiation up to 14eV have also been reported and discussed. [Copyright &y& Elsevier]

Abstract: We report the optical and dielectric properties of ZnTe1−x O x ternary alloys in the zinc-blende structure. The calculations are performed using the full potential linearized augmented plane wave (FP-LAPW) method within the density functional theory (DFT) in the generalized gradient approximation (GGA) of Engel–Vosko. Features such as optical response function, spectral dependence of refractive index and the reflectivity spectrum as well as their dependence on oxygen concentration have been studied. The agreement between our results and data available in the literature is reasonably good. The present study spans very important technological visible/ultraviolet spectral region. [Copyright &y& Elsevier]

Abstract: Li2PtH6 and Na2PtH6 are good candidate for hydrogen storage. The structural, elastic, electronic and optical properties of Li2PtH6 and Na2PtH6 compounds have been investigated using pseudo-potential plane–wave method based on the density functional theory. Computed lattice constant and H atom positional parameter at equilibrium agree well with the available experimental data. A quadratic pressure dependence of the elastic stiffness is found. A set of isotropic elastic parameters and related properties, namely bulk and shear moduli, Young''s modulus, Poisson''s ratio, average sound velocity and Debye temperature are numerically estimated in the framework of the Voigt–Reuss–Hill approximation for Li2PtH6 and Na2PtH6 polycrystalline aggregate. The analyses of the band structure indicates that Li2PtH6 and Na2PtH6 are indirect gap semiconductors. The static dielectric constant and static refractive index are inversely proportional to the fundamental gap. [Copyright &y& Elsevier]

Abstract: Theoretical investigations of the optical and dielectric properties of Cd 1− xZnxSe with zinc-blende crystal structure are reported. The calculations are mainly based on the pseudopotential framework within the virtual crystal approximation in which the effect of compositional disorder is involved. A meaningful agreement with the experimental optical band-gap bowing parameter is only obtained when the disorder effect is included in the calculation. The zinc concentration dependence of the selected features of Cd 1− xZnxSe, such as energy band-gaps, refractive index and dielectric constants has been examined. All studied quantities are found to vary monotonically with zinc concentration x. The high-frequency and static dielectric constants have been scaled with the fundamental band-gap energy (Eg ). Such scaling showed that the variation of the dielectric constants versus Eg exhibits a non-linear behavior. [Copyright &y& Elsevier]

Abstract: We present a theoretical study of the electronic structure and optical properties of zinc-blende GaSb1− x N x semiconducting dilute alloys for small amounts of N (0⩽x⩽0.05). Our calculations are based on the pseudo-potential scheme within the virtual crystal approximation that takes into consideration the effects of compositional disorder. In agreement with previous studies, it is found that the introduction of only a few percent of N into GaSb reduces substantially the energy band gaps. It is shown that GaSb1− x N x can be a direct or an indirect semiconductor depending on the N content. Negative band gaps in the material of interest are predicted to occur when the N concentration exceeds 0.026. The information derived from the present study shows that GaSb1− x N x (0⩽x⩽0.017) should enable access to wavelengths in the 2–4μm range. [Copyright &y& Elsevier]

In order to expand the scope of application of ternary nitrides and explore more thoroughly their potential as novel materials, ab initio calculations founded on density functional theory are executed to examine the mechanical, electronic, optical and transport properties of Ca 5 Si 2 N 6 and Sr 5 Ge 2 N 6 nitrides. These compounds are thermodynamically stable established on coherent energy and enthalpy of formation, with Ca 5 Si 2 N 6 having the best stability. The estimated values of elastic constants and their derived properties suggest that the items under examination are mechanically stable, ductile and elastically anisotropic. Electronic properties have been evaluated using the GGA and TB-mBJ exchange-correlation potentials. The band structure calculated via TB-mBJ reveals that these nitrides are semiconductors, where Ca 5 Si 2 N 6 has a direct energy gap of 3.55 eV and Sr 5 Ge 2 N 6 an indirect band-gap of 3.15 eV. By combining Debye temperature and band-gap values, it was concluded that the nitridosilicate compound can be used as phosphor material. According to the optical response, which was examined in terms of dielectric function, complex refractive index, absorption, reflectivity and energy damage function, the potential applications of Ca 5 Si 2 N 6 and Sr 5 Ge 2 N 6 have been discussed. Further, thermoelectric properties are computed utilizing the semi-classical Boltzmann transport notion. The obtained results show a large strength operator and depressed thermal conductivity driving to rising figure of merit values, particularly at 300 K (0.978–0.986), signifying that the studied ternary nitrides are favorable nominees for thermoelectric employments at both low and room temperatures. • The calculated elastic constants suggest that Ca 5 Si 2 N 6 and Sr 5 Ge 2 N 6 nitrides are mechanically stable, ductile and elastically anisotropic. • The calculated band structure shows that Ca 5 Si 2 N 6 has a direct gap of 3.55 eV whereas Sr 5 Ge 2 N 6 is an indirect gap of 3.15 eV. • The combination of Debye temperature and band-gap values, showed that the nitridosilicate compound can be used as phosphor material. • The optical response has permitted the discussion on the potential applications of Ca 5 Si 2 N 6 and Sr 5 Ge 2 N 6 materials. • The nitrides Ca 5 Si 2 N 6 and Sr 5 Ge 2 N 6 are found to be favorable nominees for thermoelectric employments at both low and room temperatures. [ABSTRACT FROM AUTHOR]

• Structural parameters of Sr 3 MgGeN 4 and Ba 3 GeMgN 4 show that both crystals are energetically stable. • The obtained elastic properties of Sr 3 MgGeN 4 and Ba 3 GeMgN 4 are strongly pressure dependent. • An analysis of electronic band structures shows that Sr 3 MgGeN 4 (Ba 3 GeMgN 4) is a semiconductor with a direct (indirect) band gap of 1.476 eV (1.194 eV). • The chemical bonding in both semiconductors Sr 3 MgGeN 4 and Ba 3 GeMgN 4 is dominated by a covalent character. • Based on the absorptive and PDOS curves, possible inter-band transition from filled VB to empty CB states could be related to electron transitions. The electronic structure, optical and thermodynamic properties of M 3 GeMgN 4 (M = Sr or Ba) nitrides have been investigated using first-principles calculations. The calculated equilibrium lattice parameters and inter-atomic bond-lengths show excellent concordance with experiment. The elastic constants (C ij s) and their derived properties have been calculated showing that the examined compounds are mechanically stable and elastically soft, ductile and anisotropic. The analysis of the electronic structure reveals a semiconductor comportment for both crystals. The Sr 3 GeMgN 4 (Ba 3 GeMgN 4) compound possesses a direct (indirect) energy gap of 1.476 eV (1.194 eV). The chemical bonding in both semiconductors is dominated by a covalent character, which originates from the Ge-N and Mg-N hybridized states. Both nitrides show moderate dielectric properties, high visible and UV absorbance, indicating that both materials are suitable for optoelectronic applications. Phononic dispersion curves have demonstrated the dynamical stability of the studied crystals. [ABSTRACT FROM AUTHOR]

Using the pseudopotential approach, we have undertaken a detailed study of the energy levels and optical properties of zinc-blende GaN spherical quantum dots as a function of their radius taken in the range 1–10 nm. Features such as energy levels, energy band gaps, electron and heavy hole effective masses, refractive index, dielectric constants and transverse effective charge have been investigated. The quantum confinement is found to be of major effect on all the studied quantities for quantum dot radius below 5 nm. Beyond 5 nm, all properties of interest tend towards retrieving the bulk properties. [ABSTRACT FROM AUTHOR]

Highlights: [•] Optical and phonon properties of Ga x In1−xAs y P1−y quaternary system. [•] Effects of disorder on optical and lattice vibration properties in Ga x In1−xAs y P1−y. [•] Lattice dynamics properties of Ga x In1−xAs y P1−y lattice matched to different substrates. [ABSTRACT FROM AUTHOR]

Abstract: The present work employs the full potential linearized augmented plane wave (FP-LAPW) technique to investigate the structural and optical properties of zinc-blende-structured ZnTe1− x O x with oxygen concentration in the range 0–1. Features such as lattice constant, bulk modulus and its pressure derivative have been reported. In agreement with X-ray diffraction measurement, it is found that the lattice constant of ZnTe1− x O x does not follow Vegard’s law. In addition, the spectral dependence of the dielectric functions of the material system of interest for various oxygen concentrations at energies below and above the fundamental absorption edge are examined and discussed. The calculated static and high-frequency dielectric constants are found to agree reasonably well with those reported in the literature. Other case, our results are predictions. The information derived from the present study may be useful for optical emitters/converters or intermediate/defect band solar cells. [Copyright &y& Elsevier]

We present spin-polarized density-functional theory calculations of the structural properties and optical spectra of Zn 1-x Co x O ternary alloys in the hypothetical zinc-blende, rocksalt and wurtzite structures. Our results are very accordant with those existing in the literature. Most of our findings are reported for the first time. Generally, the rocksalt structure is found to have the highest stiffness as compared to those of zinc-blende and wurtzite structures. The lattice parameters of alloys of interest vary in a non-linear way and hence do not obey to the Vegard's law. Analysis of the optical spectra shows that all optical features of interest are affected by both alloying and variation of structure giving thus novel optical properties. Moreover, it shows a good optical absorption in a wide photon energy range which seems to be more important for the rocksalt structure. The static refractive index values are reported for the different structures and for various compositions x. [ABSTRACT FROM AUTHOR]

The optical properties, namely the dielectric function, the refractive index, the absorption coeffcicient and the reflectivity of rocksalt MgO have been investigated using ab intio molecular dynamics calculations. The evolution of the properties of interest as a function of temperature taken in the range 50–900 K is addressed and discussed. [ABSTRACT FROM AUTHOR]