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First principles study of polymorfy of Ni and Co thin layers
Zelený, Martin ; Šob, Mojmír
The total energy profiles of trigonal and hexagonal bulk Ni and Co are employed to advance our understanding of epitaxial growth of Ni and Co thin films on various fcc(111) substrates. For nickel films, we predict the fcc stacking in the neighbourhood of the ground state and for the distance of nearest neighbors larger than 5.18 a.u. the film should exhibit hcp layer stacking. Cobalt films behave differently. The hcp phases are energetically more favorable in whole region studied.
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Analýza elektronové struktury Lavesových fází obsahujících chrom
Houserová, Jana ; Šob, Mojmír
Binary systems containing chromium can be found in many kinds of steels where the Laves-phase can be considered as a potential candidate for strengthening provided size and distribution of the particles are within certain limits. We performed electronic structure calculations to study the thermodynamic and structural properties of the C14 Laves phase with various compositions. In the frame of the thermodynamic study, we have evaluated the total energies of formation of Laves phase structure with different occupations of sublattices (Cr2Cr, Cr2X, X2Cr, X2X, where X stands for Fe, Mo, Si, Ta and W) with respect to the Standard Element Reference (SER) states. These energies of formation are of great importance for prediction of stability of studied configurations.
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Ab initio studie Lavesových fází v systémech Fe-Cr, Fe-Mo a Fe-Ta
Houserová, Jana ; Šob, Mojmír
Binary systems Fe-Cr, Fe-Mo and Fe-Ta can be found in many kinds of steels where the Laves-phase can be considered as a potential candidate for strengthening provided size and distribution of the particles are within certain limits. We performed electronic structure calculations to study the thermodynamic and structural properties of the C14 Laves phase with various compositions. In the frame of the thermodynamic study, we have evaluated the total energies of formation of Laves phase structure with different occupations of sublattices (Fe2Fe, Fe2X, X2Fe, X2X, where X stands for Cr, Mo and Ta) with respect to the Standard Element Reference (SER) states. These energies of formation are of great importance for prediction of stability of studied configurations.
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Ab initio calculations of theoretical strength and phase stability in copper
Černý, M. ; Šob, Mojmír ; Šandera, P.
Simulation of tensile test of copper cryslat along <001> is performed using ab initio full-potential linear augmented plane waves (FLAPW) method. Both the local density approximation (LDA) and generalized gradient approximation (GGA) are used to evaluate exchange-correlation contribution to the total energy. Equilibrium lattice parameter and Young modulus are computed ro assess reliability of our results by comparing them with experiment. Stability conditions for uniaxially loaded system are presented and analyzed. Finally, the ideal strength (IS) is calculated.
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