K. I. Shein

Band structure and the magnetic and elastic properties of SrFeO3 and LaFeO3 perovskites

The band structure and the magnetic and elastic characteristics of SrFeO3 and LaFeO3 perovskites with ferromagnetic and antiferromagnetic collinear spin configurations (of the A, C, and G types) are investigated using the ab initio pseudopotential method (the VASP program package) with the inclusion of the single-site Coulomb correlations (the LSDA + U formalism). It is shown that, in the pressure range 0–50 GPa, the most stable states are the ferromagnetic metal state for the SrFeO3 compound and the antiferromagnetic insulator state of the G type for the LaFeO3 compound.

Effects of atomic relaxation and the electronic structure of niobium (100) and (110) surfaces

A comparative analysis of the atomic relaxation and electronic structure of niobium (100) and (110) surfaces has been carried out using the VASP-PAW method. The relaxation-induced changes in interlayer spacings of surface layers demonstrate an oscillating behavior but they substantially differ for the two analyzed surfaces; namely for the (110) surface with the closest atomic packing two outermost surface layers are contracted by 4.3% and the relaxation becomes noticeable for three outer layers, while for the more “open” (100) surface these quantities equal 13.1 and six layers, respectively. An analysis of the layer-by-layer distribution of the densities of states, spatial distribution of the charge density, and densities of states at the Fermi level indicates that the most considerable changes near Fermi level take place for (100) surface.

Elastic properties of thorium ceramics ThX (X = C, N, O, P, As, Sb, S, Se)

The elastic constants (C11, C12, and C44) of all the known cubic binary phases of thorium with non-metals, ThX (X = C, N, O, P, As, Sb, S, Se), have been calculated using the full-potential linearized augmented plane wave (FLAPW) method with an exchange-correlation potential in the generalized gradient approximation (GGA). Numerical estimates of elastic parameters of the corresponding polycrystalline ceramics (bulk compression modulus, shear modulus, Young’s modulus, Poisson’s ratio, and Lamé’s coefficients) are obtained and analyzed for the first time.