Sharif Digital Repository

The electronic structure of BaFe2-xNixAs2 (x = 0, 1, 2) as a function of Ni doping has been investigated. Electronic density of states and the band structures are calculated within the first-principle density functional theory for non-magnetic phase. Pseudopotential quantum espresso code in the generalized gradient approximation has been used. Lattice and ionic position parameters of the system have been taken from the experimental data and have been optimized to find the equilibrium structure parameters. The electronic structure is characterized by a sharp Fe/Ni3d peak close to the Fermi level and is dominated by Fe/Ni3d and As4p hybridized states similar to the other Fe-based... 

The crystal and electronic structures of normal phase of Ba1-xKxFe2As2 for x = 0.0, 0.5 and 1.0 have been studied by using pseudopotential Quantum Espresso code based on ab-initio density functional theory. Effects of K doping on the crystal structure and lattice parameters have been calculated and compared with the experimental and computational reported data for similar compounds. The metal-metal bonding scenario was used to explain the changes of lattice parameters by K doping. The electronic structure of this system including of density of states and band structure have been calculated and investigated by K doping. One of the interesting results is that a larger peak is appeared near the... 

The equilibrium crystal structure and electronic structure of BaFe2-x Cox As2 (x = 0,1, 2) superconductor have been investigated by using the pseudopotential Quantum Espresso code based on the ab initio density functional theory in the generalized gradient approximation. The equilibrium crystal structure for x = 1.0 has been determined by considering five different Fe/Co configurations. This study shows that the spin calculation is essential to obtain the experimental values at x = 0.0. The total and partial density of states, band structure, and Fermi surfaces of the three compounds has been calculated. Density of states calculation indicates the important... 

The effects of fluorine doping on the electronic structure of LaO1−xFxFeAs superconductor have been investigated by ab initio density functional theory using pseudopotential quantum espresso code. Firstly, we have studied the role of fluorine doping on the electronic structure of LaO1−xFxFeAs by calculation of band structure, density of states, and Fermi surfaces at various doping levels x = 0.00, 0.25, and 0.50. The lattice parameters and ionic position have been determined by optimizing crystal structure. Our results show that doping decreases cell volume similar to mechanical pressure and shifts the bands and states near the Fermi level toward the lower energies. According to the Fermi... 

We have studied the pressure-induced structural, magnetic and electronic properties of AeFe 2 As 2 (Ae = Ba, Sr, Ca) compounds in the framework of density functional theory within the GGA-PBE method. The effects of chemical pressure generated by Sr and Ca substitutions in BaFe 2 As 2 have been investigated. We have found a magnetic transition at the same primitive unit cell volume, around 81 Å 3 for the (Ba⧹Ca)Fe 2 As 2 compounds, which predicts a magnetic transition pressure of 12 GPa for SrFe 2 As 2 . The structural parameters of FeAs 4 tetrahedra are obtained after ionic relaxation and compared with the existing experimental results. The change of these internal parameters is ascribed to... 

Electronic and phonon structures of the BaFe2As2 superconductor in the magnetic-orthorhombic phase have been investigated by the ab-initio density functional theory using the pseudopotential Quantum Espresso code. Density of state and electronic band structure for this phase has been studied, but phonon dispersion has been obtained only for the nonmagnetic-orthorhombic phase. Electronic band structure and density of states are in good agreement with other calculations in the literature. The electronic state near the Fermi energy are essentially made from Fe3d and As4p orbital that indicate in-plane conductivity in FeAs layers in this system. Comparing calculated phonon dispersions with...