National Repository of Grey Literature 29 records found  beginprevious18 - 27next  jump to record: Search took 0.01 seconds. 
Transition between close-packed structures in palladium
Káňa, Tomáš ; Hüger, E. ; Šob, Mojmír
Possible mechanisms of hcp-fcc phase transition in Pd are studied with the help of ab initio electronic structure calculations.
Studium elektronové struktury a krystalických fází teluru z prvních principů
Hemzalová, P. ; Legut, Dominik ; Šob, Mojmír
We study the energetics of seven crystalline phases of tellurium (trigonal, rhombohedral, orthorhombic, monoclinic, simple cubic, body-centered cubic and face-centered cubic phase) from first principles in order to reveal the relation between them and to advance our fundamental understanding of behavior of tellurium at high pressures.
Studium magnetismu hranic zrn z prvních principů
Čák, Miroslav ; Šob, Mojmír ; Hafner, J.
Grain boundaries (GBs) represent an important class of two-dimensional extended defects in materials. Segregation of impurity atoms is responsible for a degradation of mechanical properties. Recently, it was found that application of magnetic annealing leads to decreasing concentration of impurities at GBs in Fe-0.8%Sn alloy and improves its ductility To understand the mechanism of this process it is necessary to study magnetism of clean GBs as well as of GBs with segregants at the microscopic (ab initio) level. In the present work, we investigate the Sigma5(310) GB in iron.
Electronic structure In-Sn alloys
Všianská, Monika ; Legut, Dominik ; Šob, Mojmír
The InSn system is interesting by the existence of a simple hexagonal phase for compositions from 72 to 87 at% Sn at 25 °C and from 73 to 85 at% Sn at -150 °C. These alloys are usually referred to as gamma–Sn. The InSn alloys are disordered in the whole concentration interval. In this contribution, energetics and electronic structure of InSn system is studied from first principles. A simplified version of virtual crystal approximation is employed to describe disorder. It turns out that the present approach is capable of describing phase composition of InSn system in the whole concentration interval. In particular, we are able to reproduce the existence of simple hexagonal phase around 80 at% Sn.
Si-obsahující Lavesovy fáze
Houserová, Jana
We performed electronic structure calculations to study the thermodynamic and structural properties of the C14 Laves phases in several systems with various compositions. In the frame of a thermodynamic study, we have evaluated the total energies of formation of Laves phase structure with different occupations of sublattices (Si2Si, Si2X, X2Si, X2X, where X stands for Cr, Fe, Mo and W) with respect to the Standard Element Reference (SER) states.
Studium magnetismu kobaltu podél tetragonální deformační dráhy z prvních principů
Zelený, Martin ; Legut, Dominik ; Šob, Mojmír
We present a study of magnetic behavior of cobalt along the tetragonal deformation path at various atomic volumes. The total energies are calculated by full-potential linearized augmented plane waves (FLAPW) method incorporated in the WIEN2k code. Calculated total energies are displayed in contour plots as functions of tetragonal distortion and volume. Borderlines between various magnetic phases are shown.
Studium magnetismu v FeCo z prvních principů
Čák, Miroslav ; Legut, Dominik ; Šob, Mojmír
Total energy of FeCo as a function of volume and tetragonal deformation is calculated. The results are used to explain and predict the lattice parameters of FeCo thin films on (001) substrates.
Magnetism and phase stability of Ni3Al structures
Legut, Dominik ; Friák, Martin ; Šob, Mojmír ; Fiala, J.
Phase stability, magnetic behavior and theoretical strength of Ni3Al is studied by means of first-principles electronic structure calculations. Total energy calculations are performed along the trigonal and tetragonal deformation paths. The phase boundaries between the ferromagnetic and non-magnetic phase are determined.
Nanoindentation and theoretical strength in metals and intermetallics
Šob, Mojmír ; Legut, Dominik ; Friák, Martin ; Fiala, J. ; Vitek, V. ; Hafner, J.
The present contribution gives an account of applications of quantum-mechanical (first-principles) electronic structure calculations to the problem of theoretical strength in metals and intermetallics. First, we briefly describe the way of simulating the tensile test and the electronic structure calculational method. Then we discuss the theoretical strength values in a number of elemental metals and intermetallics and compare them with available experimental data, both from measurements on whiskers and from nanoindentation experiments.
Ab initio simulation of three-axial deformation of perfect iron crystal
Černý, M. ; Šandera, P. ; Pokluda, J. ; Friák, Martin ; Šob, Mojmír
Ab initio electronic structure calculations of ideal strength, bulk modulus and equilibrium lattice parameter of iron in the body-centered-cubic lattice under three-axial tension are performed using the linear muĆn-tin orbitals method in atomic sphere ap proximation (LMTO-ASA) and the full-potential linearized augmented plane waves method (FLAPW). Magnetic ordering was taken into account by means of spin-polarized calculation. Two exchange-correlation energy approximations were employed, namely the local (spin) den-sity approximation (LDA) and the generalized gradient approximation (GGA). Computed values are compared with experimental data.

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