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Abstract: An ab initio study of the band structure, density of states, topology of the electron density and the spectral features of the linear and non-linear optical properties of the Ga2AsSb chalcopyrite are presented. The lattice parameters (a, c), the internal structure parameter, u, describing the position of Ga atom and the (c/a) ratio are optimized. The covalent bonding character is predicted via analyzing the electron density at the equilibrium geometry. The linear optical properties namely the real and imaginary parts of dielectric function, reflectivity, electron energy loss function and refractive index are calculated. This compound has a large uniaxial dielectric anisotropy and a large negative birefringence. Based on the density functional theory the non-linear optical properties are calculated and their spectra are analyzed. [ABSTRACT FROM AUTHOR]

Abstract: A theoretical study of structural, electronic, linear and nonlinear optical properties of ZnIn2Te4 defect-chalcopyrite is presented using the full-potential linearized augmented plane-wave (FP-LAPW) method. The exchange and correlation potential is treated by the generalized-gradient approximation (GGA). Moreover, the Engel and Vosko GGA formalism (EV-GGA) is also used to improve the band gap results. The lattice parameters ( a , c ) and the atomic positions (x, y and z) are optimized and found in good agreements with the available experimental data. Our calculations performed for band structure and density of state show that the valence band maximum (VBM) and conduction band minimum (CBM) are located at Γ resulting in a direct energy gap of about 0.89eV for GGA and 1.20eV for EV-GGA. The linear optical properties namely, the real and imaginary parts of the dielectric function and the reflectivity spectrum are calculated. This compound possesses a considerable negative birefringence. Based on the density functional theory the nonlinear optical properties are calculated and their spectra are analyzed. [ABSTRACT FROM AUTHOR]

Abstract: The structural and elastic behaviour of the chalcopyrite SbPGa2 and SbAsGa2 crystals has been determined by means of first principles calculations using the full-potential augmented plane wave (FPLAPW) method. Ground state properties such as the lattice parameters (a, c and u), bulk modulus B, its pressure derivative B′, have been directly calculated and compared to previous experimental and theoretical results when available. We have determined the elastic parameters (C 11, C 12, C 33, C 44 and C 66), which have not been calculated and measured yet. Thermal properties, including the linear and cubic expansion coefficients and the heat capacity, have been estimated using a quasi-harmonic Debye model. To our knowledge this is the first quantitative theoretical prediction of elastic and thermal properties for these compounds and still awaits experimental confirmations. [Copyright &y& Elsevier]