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Structure and magnetism of iron and iron overlayers from the first principles
Friák, Martin ; Šob, Mojmír ; Vitek, V.
A detailed theoretical study of magnetic behavior of iron along the bcc fcc (Bain's) transformation paths at various atomic volumes is presented. The total energies are calculated by spin polarized full potential LAPW method and are displayed in contour plots as functions of tetragonal distortion c/a and volume; borderlines between various magnetic phases are shown. Stability of tetragonal magnetic phases of fl Fe is discussed. The calculated phase boundaries are used to predict the lattice parameters and magnetic states of iron overlayers on various (001) substrates.
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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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Ab initio simulation of a tensile test in iron
Friák, Martin ; Šob, Mojmír ; Vitek, V.
A tensile test in ferromagnetic and nonmagnetic iron is simulated by ab initio electronic structure calculations using all-electron full potential linearized augmented plane wave method (FLAPW) within generalized gradient approximation (GGA). The theoretical tensile strength of ferromagnetic iron for [001] loading is determined and compared with that of other materials. The magnetic behavior of iron under tensile loading is studied in detail and compared with results for triaxial loading.
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Ab initio study of displacive phase transformations in iron
Friák, Martin ; Šob, Mojmír ; Wang, L. G. ; Vítek, V.
The bcc-hcp and bcc-fcc transformations in iron are studied ab initio by following a constant-volume one-parameter transformation paths. Calculation make it possible to locate, the transition configuration at which the bcc ferromagnetic structure transforms into the hcp nonmagnetic structure as well as the transition from the high-spin state to a low-spin state along the bcc-fcc transformation path.
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Grain boundary segregation in ordered alloys
Lejček, Pavel
Grain boundary segregation of solutes in systems with different level of the order is referred.Obtained temperature dependences of chemical composition of grain boundaries in Fe-Si, Fe-Al and NiAl systems are discussed from the point of view of present understanding of segregation in ordered systems.
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