[en] The magnetic stability and electronic properties of the FeO compound are investigated using the framework of an all-electron full-potential linearized augmented-plane wave (FP-LAPW) method within the generalized gradient (GGA) and GGA+U approximations. We locate the ground state to be of rhombohedrally distorted B1 structure with compression along [111] direction. The values for the band gap and magnetic moments obtained with this parameter-free first principles method are in good agreement with experimental data. Finally, we conclude that the treatment of the correlated electrons (GGA+U) approach with the inclusion of spin-orbit-coupling (SOC) is important for the correct description of this compound.

[en] The ground-state properties of ZnO in the rock-salt (B1), CsCl (B2), zinc-blende (B3), wurtzite (B4), cinnabar, cmcm, d-β-tin, NiAs, Immm, and Imm2 structures were investigated using an accurate first-principles total-energy calculations based on the full-potential augmented plane-wave plus local orbitals (APW+lo) method. The local density approximation was used for the exchange and correlation energy density functional. The ground state properties such as lattice parameter, bulk modulus and its pressure derivative as well as the structural phase stability were calculated and compared to the available experimental data and previous theoretical works

[en] We have investigated the structural properties of seven different structure types of Mg₂Si which include the cubic CaF₂, orthorhombic PbCl₂, hexagonal Ni₂In, tetragonal Al₂Cu, Laves phase (cubic MgCu₂), hexagonal MgZn₂ and dihexagonal MgNi₂ type of structures, using a full potential linearized augmented plane wave method as implemented in WIEN₂k within the framework of density functional theory. The exchange-correlation potential is treated by the new form of generalized gradient approximation (GGA-PBEsol). In total energy calculations it is clearly seen that cubic CaF₂-type structure is stable at ambient conditions, and it undergoes a first-order phase transition to orthorhombic PbCl₂-type, then to the hexagonal Ni₂In-type structure and finally to the cubic Laves phase MgCu₂-type. A new structure type is predicted to be stable at high pressure. Moreover, we intend to combine the electronic structure calculations performed by mean of generalized gradient approximation and modified Becke-Johnson potential with Boltzmann transport theory as incorporated in BoltzTraP code to interpret and predict the thermoelectric performance of each stable phase as a function of the chemical potential at various temperatures. We find a high thermoelectric thermopower values in cubic CaF₂-type structure that could promise an excellent candidate for potential thermoelectric applications. (author)