| 1. |
- Glazyrin, K., et al.
(författare)
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Importance of Correlation Effects in hcp Iron Revealed by a Pressure-Induced Electronic Topological Transition
- 2013
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 110:11, s. 117206-
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Tidskriftsartikel (refereegranskat)abstract
- We discover that hcp phases of Fe and Fe0.9Ni0.1 undergo an electronic topological transition at pressures of about 40 GPa. This topological change of the Fermi surface manifests itself through anomalous behavior of the Debye sound velocity, c/a lattice parameter ratio, and Mossbauer center shift observed in our experiments. First-principles simulations within the dynamic mean field approach demonstrate that the transition is induced by many-electron effects. It is absent in one-electron calculations and represents a clear signature of correlation effects in hcp Fe.
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| 2. |
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| 3. |
- Isaeva, E. I., et al.
(författare)
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Ab initio phonon calculations for Ll(2) Ni3Al and B2NiAl
- 2004
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Ingår i: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; 129:12, s. 809-814
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Tidskriftsartikel (refereegranskat)abstract
- The phonon spectra and phonon density of states of the Ni3Al and NiAl intermetallic compounds are calculated from first principles using the linear response method in conjunction with ultrasoft pseudopotentials. The calculated phonon dispersion curves are in good agreement with available experimental results from inelastic neutron scattering.
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| 4. |
- Abrikosov, I. A., et al.
(författare)
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Correlation between electronic structure, magnetism and physical properties of Fe-Cr alloys : Ab initio modeling
- 2008
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Ingår i: MATERIALS ISSUES FOR GENERATION IV SYSTEMS. - Dordrecht : Springer Netherlands. ; , s. 153-168
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Konferensbidrag (refereegranskat)abstract
- We review recent developments in the field of ab initio electronic structure theory and its application for studies of phase stability of alloy systems. Basic ideas behind state-of-the-art techniques for first-principles theoretical simulations of the phase stabilities and properties of intermetallic compounds and alloys based on the density functional theory are outlined. We concentrate on methods that allow for an efficient treatment of disorder effects, and illustrate their predictive power for the case of Fe-Cr system. We show that in the ferromagnetic alloys there are peculiarities of the mixing enthalpy in the low-Cr region in the bee phase. Thus the stability of the Cr containing steels stems from the negative mixing enthalpy at low concentrations of chromium. We explain the effect by the strong concentration dependence of the interatomic interactions in Fe-Cr system.
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| 5. |
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| 6. |
- Abrikosov, I. A., et al.
(författare)
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Multiscale approach to theoretical simulations of materials for nuclear energy applications : Fe-Cr and Zr-based alloys
- 2013
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Ingår i: Advances in materials for nuclear energy. - : Materials Research Society. - 9781605114910 ; , s. 3-14
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Konferensbidrag (refereegranskat)abstract
- We review basic ideas behind state-of-the-art techniques for first-principles theoretical simulations of the phase stabilities and properties of alloys. We concentrate on methods that allow for an efficient treatment of compositional and thermal disorder effects. In particular, we present novel approach to evaluate free energy for strongly anharmonic systems. Theoretical tools are then employed in studies of two materials systems relevant for nuclear energy applications: Fe-Cr and Zr-based alloys. In particular, we investigate the effect of hydrostatic pressure and multicomponent alloying on the mixing enthalpy of Fe-Cr alloys, and show that in the ferromagnetic state both of them reduce the alloy stability at low Cr concentration. For Zr-Nb alloys, we demonstrate how microscopic parameters calculated from first-principles can be used in higher-level models.
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| 7. |
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| 8. |
- Bergqvist, Lars, 1976-, et al.
(författare)
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Magnetic and electronic structure of (Ga1-xMnx)As
- 2003
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 67:20, s. 205201-
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Tidskriftsartikel (refereegranskat)abstract
- We present theoretical calculations of the magnetic and electronic structure of Mn-doped GaAs (in the zinc-blende structure). The magnetic properties are shown to be very sensitive to structural defects, in particular, As antisite defects and Mn at interstitial positions. Only when considering such defects can the experimental magnetic moments be reproduced by first-principles theory. We present a simple model for understanding the connection between the magnetic ordering and the As antisites, and the way in which the defects help to stabilize a partial disordered local-moment state. The connection between the energetics of the Mn substitution and the As antisite concentration is also analyzed. In addition, we compare the calculated magnetic properties and electronic structures of Mn situated on substitutional sites (Mn replacing a Ga atom) and on interstitial sites, where in agreement with observations the interstitial site is found to be less favorable. Finally, combining our first-principles calculations of the spin-wave excitation energies with a classical Heisenberg Hamiltonian we have calculated interatomic exchange interactions, and using Monte Carlo simulations we present theoretical values of the critical temperature as a function of Mn concentration.
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| 9. |
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| 10. |
- Chioncel, L., et al.
(författare)
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Ab initio electronic structure calculations of correlated systems : An EMTO-DMFT approach
- 2003
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 67:23
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Tidskriftsartikel (refereegranskat)abstract
- We propose a self-consistent method for electronic structure calculations of correlated systems, which combines the local spin-density approximation (LSDA) and the dynamical mean field theory (DMFT). The LSDA part is based on the exact muffin-tin orbital approach, meanwhile the DMFT uses a perturbation scheme that includes the T matrix with fluctuation exchange approximation. The current LSDA+DMFT implementation fulfills both self-energy and charge self-consistency requirements. We present results on the electronic structure calculations for bulk 3d transition metals (Cr, Fe, and Ni) and for Fe/Cr magnetic multilayers. The latter demonstrates the importance of the correlation effects for the properties of magnetic heterostructures.
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