a b s t r a c tStructural properties, electronic band structure, real and imaginary parts of complex dielectric function of alkali chloride XCl (K, Rb and Li) compounds were investigated under various pressures using first principles calculations. Moreover, Gibbs free energies were also calculated at those pressures. Calculated results of the Gibbs free energy show that LiCl does not show any structural phase transition. However, structural phase transitions of KCl and RbCl occur from NaCl (B1) to CsCl (B2) at 4.5 and 1.7 GPa pressures, respectively. The electronic band gaps under pressure were also calculated. The calculated physical properties of these compounds are compared with the previous theoretical and experimental results and a good agreement was observed.

Abstract:Using the first-principles band-structure method, we have calculated the structural and electronic properties of zincblende TlAs, TlP, GaAs and GaP compounds and their new semiconductor Tl Ga 1− As P 1− quaternary alloys. Structural properties of these semiconductors are obtained with the Perdew and Wang local-density approximation. The lattice constants of Tl Ga 1− As, Tl Ga 1− P ternary and Tl Ga 1− As P 1− quaternary alloys were composed by Vegard's law. Our investigation on the effect of the doping (Thallium and Arsenic) on lattice constants and band gap shows a non-linear dependence for Tl Ga 1− As P 1− quaternary alloys. The band gap of Tl Ga 1− As P 1− , E ( ) concerned by the compositions and . To our awareness, there is no theoretical survey on Tl Ga 1− As P 1− quaternary alloys and needs experimental verification. 71.15.Mb, PACS (2008): Keywords:density functional theory • electronic structure of disordered solids • electron density of states and band structure of crystalline solids © Versita sp. z o.o.

a b s t r a c tIn this paper, we investigated electronic, optic, elastic, dynamic and thermodynamic properties of RbAu compound by density functional theory within the generalized gradient approximation. The calculated static value of real part of dielectric constant is 6.7. The calculated electronic band structure of RbAu shows that RbAu is a semiconductor with an indirect band gap of 0.36 eV. Besides, RbAu obeys mechanical stability and it demonstrates elastic anisotropy. 540K is classical limit for specific heat of RbAu.

Abstract:The structural, electronic, optical and dynamical properties of CsAu compound in the CsCl(B2) phase were investigated using the density functional theory (DFT) within the generalized gradient approximation (GGA). The calculated lattice constant, static bulk modulus and first-order pressure derivative of the bulk modulus are reported and compared with previous experimental and theoretical calculations. The calculated electronic band structure for this compound is in good agreement with available theoretical and experimental studies. The present band calculation indicates that CsAu compound has an indirect gap at R→X points. Furthermore, the linear photon-energy-dependent dielectric functions have been calculated. For the first time, the electronic structure results are used, within the implementation of a linear-response technique, for calculations of phonon properties.PACS (2008)

-The geometric structural optimization, electronic band structure, total density of states for valence electrons, density of states for phonons, optical, dynamical, and thermodynamical features of cesium chloride have been investigated by linearized augmented plane wave method using the density functional theory under the generalized gradient approximation. Ground state properties of cesium chloride are studied. The calculated ground state properties are consistent with experimental results. Calculated band structure indicates that the cesium chloride structure has an indirect band gap value of 5.46 eV and is an insulator. From the obtained phonon spectra, the cesium chloride structure is dynamically stable along the various directions in the Brillouin zone. Temperature dependent thermodynamic properties are studied using the harmonic approximation model.

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The electronic structure, density of states and linear optical properties of NaCdF3 are studied using density functional methods in the local density approximation (LDA) and the generalized gradient approximation (GGA). The calculated band structure of NaCdF3 shows a direct band gap at the Γ‐point in the Brillouin zone. The structural optimization of NaCdF3 is performed using the LDA and the GGA. The calculated structural optimization of NaCdF3 is compared with previous results and is found to be in good agreement with those results. The optical spectra of NaCdF3 in the photon energy range up to 30 eV are investigated under the scissor approximation. The real and imaginary parts of the dielectric function as a function of the photon energy and hence optical constants such as refractive index, energy loss for volume and surface, extinction coefficient, reflectivity and absorption coefficient have been calculated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)