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Compositional variations in GaAs based ternary alloys have exhibited wide range alterations in electronic properties. In the present paper, first-principles study of GaAsxSb1 – x ternary alloys have been presented and discussed. Density functional theory (DFT) computation based on the full-potential (linearized) augmented plane-wave (FP-LAPW) method has been utilized to calculate the Density of States (DOS) and the band structure of ternary alloys GaAsxSb1 – x (x = 0, 0.25, 0.50, 0.75, 1). The calculations were performed using the exchange-correlation energy functional from Perdew, Burke, and Ernzerhof, a generalized-gradient approximation (GGA-PBE) and Becke–Johnson exchange potential with local-density approximation (BJLDA) available within the framework of WIEN2k code. As compared to PBE, the results obtained from BJLDA are in close agreement with other experimental works. The DOS results show a reduction in bandgap as the Sb fraction is increased in GaAsxSb1 – x ternary alloys. The bandgap obtained by PBE and BJLDA are found to deviate from Vegard's law, i.e., it doesn't vary linearly with composition. However, the bandgap obtained by BJLD is found to closely match Vegard's law when the bowing parameter is considered. [ABSTRACT FROM AUTHOR]

Compositional variations in GaAs based ternary alloys have exhibited wide range alterations in electronic properties. In the present paper, first-principles study of GaAsxSb1 –x ternary alloys have been presented and discussed. Density functional theory (DFT) computation based on the full-potential (linearized) augmented plane-wave (FP-LAPW) method has been utilized to calculate the Density of States (DOS) and the band structure of ternary alloys GaAsxSb1 –x (x = 0, 0.25, 0.50, 0.75, 1). The calculations were performed using the exchange-correlation energy functional from Perdew, Burke, and Ernzerhof, a generalized-gradient approximation (GGAPBE) and Becke-Johnson exchange potential with local-density approximation (BJLDA) available within the framework of WIEN2k code. As compared to PBE, the results obtained from BJLDA are in close agreement with other experimental works. The DOS results show a reduction in bandgap as the Sb fraction is increased in GaAsxSb1 –x ternary alloys. The bandgap obtained by PBE and BJLDA are found to deviate from Vegard's law, i.e., it doesn't vary linearly with composition. However, the bandgap obtained by BJLD is found to closely match Vegard's law when the bowing parameter is considered. [ABSTRACT FROM AUTHOR]

Ab initio calculations for the Linear Macroscopic Dielectric analyses of CH3NH3BiBr3 and CH3NH3GaBr3 (having 8.33% dopant replacement percentage each) as possible replacements for the Lead based perovskite CH3NH3PbBr3 were done in this work using Perdew-Burke-Ernzerhof functional of Density Functional Theory as implemented by FHI-aims Code. Optimized lattice constants were calculated for CH3NH3BiBr3 and CH3NH3GaBr3 to be 9.10 Å and 8.27 Å respectively. The Lowest Unoccupied Molecular Orbital (LUMO), Highest Occupied Molecular Orbital (HOMO) and calculated band gap, Band Structure and Density of States (DOS) plots were made to analyse the band structures of these crystals and they were found to be metallic with a band gap of 0.00018636 eV and 0.00022286 eV for CH3NH3BiBr3 and CH3NH3GaBr3 respectively. The imaginary and real parts of the inter-band and intra-band contribution to the linear dielectric tensor within the e imagi Random Phase Approximation (RPA) of the optical properties of these perovskites were calculated and an average dielectric tensor of 3.1209467 and 2.789173 was found for CH3NH3BiBr3 and CH3NH3GaBr3 respectively. From the absorption data and dielectric tensor components calculated, both materials have an average absorption peak at frequency of 16.5373nm at 1.006567 MeV, 16.2040nm at 1.227600 MeV respectively, across all cubic planes. [ABSTRACT FROM AUTHOR]