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Full-potential linear muffin-tin (FP-LMTO) has been implanted within density functional theory (DFT) and within local density approximation. The structural and electronic properties of GaP, AlP and ScP binary compounds and their ternary alloys Sc x Al 1− x P and Sc x Ga 1− x P over a whole range of compositions (0≤ x ≤1) and the superlattices Sc 0.25 Ga 0.75 P/Sc 0.5 Ga 0.5 P and Sc 0.25 Al 0.75 P/Sc 0.5 Ga 0.5 P in the zinc-blende structure are investigated. The calculated resulted gave reasonable agreements with other published data. [ABSTRACT FROM AUTHOR]

Abstract: An accurate ab initio full potential linear muffin-tin orbital method has been used to investigate the structural, electronic and optical properties of BP, BAs and their (BP) n /(BAs) n superlattices (SLs). The exchange-correlation potential is treated with the local density approximation of Perdew and Wang (LDA-PW). The calculated structural properties of BP and BAs compounds are in good agreement with available experimental and theoretical data. It is found that BP, BAs and their alloys exhibit an indirect fundamental band gap. The fundamental band gap decreases with increasing the number of monolayer n. The optical properties show that the static dielectric constant significantly decreases in superlattices compared to their binary compounds. [Copyright &y& Elsevier]

Abstract The ground state, electronic and optical properties of the quaternary Be x Cd 1-x Te y S 1-y lattice matched to CdS substrate has been predicated in detail via first principles calculations. A full potential linearized augmented plane wave (FP LAPW) method has been employed in conjunction with the generalized gradient approximation (GGA) to investigate the influence of increasing the concentration of beryllium and tellurium atoms with 0.25 step value (0 < x < 1 and 0 < y < 1) on the structural parameters such as the equilibrium lattice constant, the bulk modulus and its first pressure derivative. They were found in good agreement with the available data. Then, we have reported the concentration dependence on the improved electronic band structure and the optical constants (real and imaginary parts of the dielectric function and the refractive index) using the Modified Becke-Johnson exchange potential. For all Be and Te incorporated amounts with (x = y = 0.25, x = y = 0.5 and x = 0.5,y = 0.75), the Be x Cd 1-x Te y S 1-y lattice matched to CdS substrate alloys exhibits a semiconducting behavior with a small lattice mismatching ratio, a direct narrow band gaps energies and a high refractive index. Looking forward at the predominant field of expertise of these alloys, they can be futurely exploited in the designing of quantum well lasers based on Be x Cd 1-x Te y S 1-y active layer /CdS barrier. [ABSTRACT FROM AUTHOR]

Abstract The Full Potential Linear Muffin-Tin Orbital (FP-LMTO) method has been used to investigate structural and electronic properties of ScP and TlP binary compounds, their Sc x Tl 1-x P ternary alloys and (ScP) n /(TlP) n superlattices for specific cases of x = 0.25, 0.5, 0.75 and n = 1, 2, 3 in the framework of the density functional theory (DFT) within the local density approximation (LDA). The ground-state properties are determined in the cubic Zinc-blende phase (ZnS). The electronic band structures of Sc x Tl 1-x P ternary alloy were calculated in the Zinc-blende phase and the material has a semi-conductor behavior with a direct band gap for x = 0.25 and an indirect band gap for x = 0.5 and 0.75. In studying the possibility to obtain new materials (ScP) n /(TlP) n , the results show that these materials are semiconductors with an indirect band gap for n = 1 and a direct band gap for n = 2 and 3. The optical properties were calculated for only three materials; Sc 0.25 Tl 0.75 P, (ScP) 2 /(TlP) 2 and (ScP) 3 /(TlP) 3 which have a direct band gap. [ABSTRACT FROM AUTHOR]

Abstract: The structural, elastic and electronic properties of NiTiSn and CoVSn half-Heusler compounds have been calculated using the full-potential linear muffin-tin orbital (FP-LMTO) method. The computed equilibrium lattice constants are in excellent agreement with the available experimental and theoretical data. The elastic constants C ij are calculated using the total energy variation with strain technique. The polycrystalline elastic moduli (namely: the shear modulus, Young''s modulus, Poisson''s ratio, Lamé''s coefficients, sound velocities and the Debye temperature) were derived from the obtained single-crystal elastic constants. The ductility mechanism for the studied compounds is discussed via the elastic constants C ij and their related parameters. The electronic band structure calculations show that the conduction band minimum (CBM) is located at the X point for both compounds, whereas the valence band maximum (VBM) is located at the Г point for NiTiSn and at the L point for CoVSn, resulting in indirect energy band gaps of 0.46 and 0.75eV for NiTiSn and CoVSn, respectively. The pressure and volume dependences of the energy band gaps have been calculated. [Copyright &y& Elsevier]