| 11. |
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| 12. |
- Johansson, Börje, et al.
(författare)
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Time distances and labor market integration
- 2002
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Ingår i: Papers in regional science (Print). - : Wiley. - 1056-8190 .- 1435-5957. ; 81:3, s. 305-327
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Tidskriftsartikel (refereegranskat)abstract
- This article investigates how time distances within and between municipalities determine the spatial extent of local and regional labor markets. As time distances change, the extent of the labor market will also change. Diminishing time distances will bring about increases in labor market size by integrating formerly spatially separate markets. We analyze such processes using accessibility measures derived from a random choice preference function approach. Accessibility is measured in terms of number of jobs, labor supply and supply of service functions. The aim of the work is to illustrate the usefulness of the purpose-specific accessibility measure we introduce.
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| 13. |
- Korzhavyi, Pavel A., 1966-, et al.
(författare)
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Ab Initio Study of Phase Equilibria in TiCx
- 2002
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Ingår i: Physical Review Letters. - : The American Physical Society. - 0031-9007 .- 1079-7114. ; 88:1, s. 015505-1-01505-4
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Tidskriftsartikel (refereegranskat)abstract
- The phase diagram for the vacancy-ordered structures in the substoichiometric TiCx (x=0.5-1.0) has been established from Monte Carlo simulations with the long-range pair and multisite effective interactions obtained from ab initio calculations. Three ordered superstructures of vacancies (Ti2C, Ti3C2, and Ti6C5) are found to be ground state configurations. Their stability has been verified by full-potential total energy calculations of the fully relaxed structures.
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| 14. |
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| 15. |
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| 16. |
- Li, S., et al.
(författare)
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Pressure-induced phase transitions of KNbO3
- 2002
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 14:44, s. 10873-10877
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Tidskriftsartikel (refereegranskat)abstract
- We studied crystal structures of potassium niobate (KNbO3) at high pressure by means of first-principles self-consistent total-energy calculations within the local density approximation using the full-potential linear muffin-tin orbital method. For the first time, we have calculated the atomic equilibrium volume, bulk modulus, total energy, and transition pressures for KNbO3, covering the full pressure range for which the above-mentioned experiments have been done. Two pressure-induced transitions are derived theoretically, namely one from orthorhombic (I) to cubic structure at around 13.2 GPa and a second from cubic to orthorhombic (II) structure at a pressure of 39.7 GPa. This fully confirms the recent experiments by Kobayashi et al (Kobayashi Y, Endo S, Ashida T, Ming L C and Kikegawa T 2000 Phys. Rev. 615819).
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| 17. |
- Magyari-Kope, B., et al.
(författare)
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High-pressure structure of ScAlO3 perovskite
- 2002
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Ingår i: Journal of Geophysical Research. - : American Geophysical Union (AGU). - 0148-0227 .- 2156-2202. ; 107:B7
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Tidskriftsartikel (refereegranskat)
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| 18. |
- Magyari-Kope, B., et al.
(författare)
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Low-temperature crystal structure of CaSiO3 perovskite : An ab initio total energy study
- 2002
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 65:19
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Tidskriftsartikel (refereegranskat)abstract
- The stability of cubic CaSiO3 perovskite with respect to octahedral rotations is investigated by ab initio total-energy calculations. The proposed theoretical ground-state crystal structure has the orthorhombic Pbnm symmetry. Pressure gradually reduces the average tilting of the SiO6 octahedra relative to the cubic axis, from 7degrees at zero pressure to 4degrees at about 150 GPa. The energy difference between the orthorhombic and cubic phases at 0 GPa is 63 meV per f.u. and shows weak pressure dependence. A possible stabilization of the cubic phase at finite temperatures by entropy effects is discussed.
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| 19. |
- Magyari-Kope, B., et al.
(författare)
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Model structure of perovskites : cubic-orthorhombic phase transition
- 2002
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Ingår i: Computational materials science. - 0927-0256 .- 1879-0801. ; 25:4, s. 615-621
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Tidskriftsartikel (refereegranskat)abstract
- We extend the revised global parametrization method (revGPM) of orthorhombic perovskites with Pbnm symmetry to describe the changes in the lattice parameters and internal atomic coordinates within a broad range of structural distortions, including the vicinity of the orthorhombic-cubic phase transition. The applicability of the revGPM in the prediction of the evolution of the structural parameters under increasing hydrostatic pressure is demonstrated through test calculations performed for geophysically important perovskites. The present results are compared with the available theoretical and experimental data.
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| 20. |
- Magyari-Kope, B., et al.
(författare)
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Origin of octahedral tilting in orthorhombic perovskites
- 2002
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 66:9
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Tidskriftsartikel (refereegranskat)abstract
- The adopted crystal structure of the ABO(3) perovskites is determined by the balance between the interaction of the semicore states of the A and B atoms and oxygen ions. Topological considerations show that the structural setup always stabilizes the cubic phase at large pressures, while small or negative pressures favor nonvanishing octahedral tiltings. As an example, we show that the structural distortion in CaSiO3 perovskite is slightly depressed with hydrostatic pressure, but it increases significantly with increasing volume.
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