Endre søk
Begrens søket
1 - 5 of 5
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Belonoshko, Anatoly B.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kondenserade materiens teori.
    Lukinov, Timofei
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Kondenserade materiens teori.
    Fu, Jie
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kondenserade materiens teori.
    Zhao, Jijun
    Davis, Sergio
    Simak, Sergei I.
    Stabilization of body-centred cubic iron under inner-core conditions2017Inngår i: Nature Geoscience, ISSN 1752-0894, E-ISSN 1752-0908, Vol. 10, nr 4, s. 312-+Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Earth's solid core is mostly composed of iron. However, despite being central to our understanding of core properties, the stable phase of iron under inner-core conditions remains uncertain. The two leading candidates are hexagonal close-packed and body-centred cubic (bcc) crystal structures, but the dynamic and thermodynamic stability of bcc iron under inner-core conditions has been challenged. Here we demonstrate the stability of the bcc phase of iron under conditions consistent with the centre of the core using ab initio molecular dynamics simulations. We find that the bcc phase is stabilized at high temperatures by a diffusion mechanism that arises due to the dynamical instability of the phase at lower temperatures. On the basis of our simulations, we reinterpret experimental data as support for the stability of bcc iron under inner-core conditions. We suggest that the diffusion of iron atoms in solid state may explain both the anisotropy and the low shear modulus of the inner core.

  • 2.
    Belonoshko, Anatoly
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Kondenserade materiens teori.
    Lukinov, Tymofiy
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Kondenserade materiens teori.
    Zhao, Jijun
    Dalian University of Technology, China.
    Fu, Jie
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Kondenserade materiens teori.
    Davis, Sergio
    Simak, Sergei
    Mechanism of the body-centered cubic iron stabilization under the Earth core conditionsManuskript (preprint) (Annet vitenskapelig)
  • 3.
    Fu, Jie
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Kondenserade materiens teori.
    Developing semi-empirical ab initio based potentials in materials modeling2016Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Ab initiocalculation based on density function theory (DFT) is an accu-rate and efficient method for modelling material properties. It is performedby solving the Shrödinger equations with a few assumptions to obtain thephysical properties of the system. It is very computational demanding whendealing with large systems or long-time simulations. Developing empiricalpotentials on the basis ofab initiocalculations on smaller systems is a possi-ble way to solve this problem. The empirical potentials will benefit from theaccuracy ofab initiosimulations and can facilitate applications to large sys-tems and long-time simulations. In this thesis, we have performed two studiesregarding fitting empirical potentials: one is fitting an empirical Sutton-Chenpotential based onab initiosimulations for iron under extreme conditionsand the other one is fitting an improved Finnis-Sinclair potential for ternaryV-Ti-Cr alloy.In the first part, we focus on fitting a Sutton-Chen potential for solid Feunder the Earth’s inner core condition. Based onab initiomolecular dynam-ics (MD) simulation results, the Sutton-Chen potential is fitted to energies ofthe configurations obtained fromab initioMD simulations at the pressure of360 GPa and temperature of 6000 K. The method applied for the fitting isthe Particle Swarm Optimization (PSO) algorithm. The Sutton-Chen poten-tial can reproduce theab initioenergies with an error of 6.2 meV/atom. Setas the same withab initioMD simulations, classical MD using Sutton-Chenpotential can obtain the consistent results with those fromab initioMD sim-ulations at the pressure of 360 GPa and temperature of 6000 K. In order toexplore the size effect on the results, we extend the classical MD to large-sizesystems (from 1024 atoms to 65536 atoms). We also extend the temperaturerange to see the temperature effect on the results.In the second part, we develop an improved Finnis-Sinclair (IFS) potentialfor ternary V-Ti-Cr alloys. The interaction parameters of V-V, Ti-Ti andCr-Cr are fitted to the experimental lattice constants, cohesive energies andelastic constants. The binary alloy potential parameters are obtained byconstructing 3 binary alloy models (V15Ti, V15Cr, V8Ti8) and fitting to theirtheoretical lattice constants, cohesive energies and elastic constants. Finally,the IFS potential is successfully used to calculate mechanical properties andthe monovacancy formation energy in V-Ti-Cr alloy. It is also applied toinvestigate the composition effect on the mechanical properties of ternaryV-Ti-Cr alloys.

  • 4.
    Fu, Jie
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Kondenserade materiens teori.
    Improved Finnis-Sinclair potential for V-Ti-Cr ternary alloysManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    We have developed an improved Finnis-Sinclair (IFS) potential for vanadium-rich body-centred cubic V–Ti–Cr random alloys. An extra exponential term is added to the original Finnis-Sinclair potential to enhance the repulsive interactions between atoms. IFS potential is fitted to experimental and theoretical lattice constants, cohesive energies, and elastic constants of the pure metals (V, Ti, and Cr) and binary alloys (V15Ti, V15Cr and Ti8Cr8). The experimental lattice constants, cohesive energies, and elastic constants of pure metals and binary alloys are well reproduced by the IFS potential. The good agreement of the predicted V mono-vacancy and self-interstitial formation energies with available experimental and theoretical data further confirms the accuracy of our IFS potential. The elastic properties and the influence of one vacancy on them are investigated for two technologically relevant alloys, V–4Ti–4Cr and V–5Ti–5Cr, using the IFS potential. The predicted results for the vacancy formation energies indicate that it is energetically easy to produce a Ti vacancy, but hard to generate a Cr vacancy in the considered alloys. Finally, this work also provides a reference method to fit empirical potentials for other ternary alloys.

  • 5.
    Fu, Jie
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kondenserade materiens teori. Ningbo Univ, Peoples R China; Dalian Univ Technol, Peoples R China.
    Zhao, Jijun
    Plyasunov, Andrey V.
    Belonoshko, Anatoly
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kondenserade materiens teori.
    Ab initio molecular dynamics study of fluid H2O-CO2 mixture in broad pressure-temperature range2017Inngår i: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 7, nr 11, artikkel-id 115217Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Properties of H2O and CO2 fluid and their mixtures under extreme pressures and temperatures are poorly known yet critically important in a number of applications. Several hundreds of first-principles molecular dynamics (FPMD) runs have been performed to obtain the pressure-volume-temperature (P-V-T) data on supercritical H2O, CO2, and H2O-CO2 mixtures. The pressure-temperature (P-T) range are from 0.5 GPa to 104 GPa (48.5 GPa for CO2) and from 600 K to 4000 K. Based on these data, we evaluate several existing equations of state (EOS) for the fluid H2O, CO2, and H2O-CO2 mixture. The results show that the EOS for H2O from Belonoshko et al. [Geochim. Cosmochim. Acta 55, 381-387; Geochim. Cosmochim. Acta 55, 3191-3208; Geochim. Cosmochim. Acta 56, 3611-3626; Comput. Geosci. 18, 1267-1269] not only can be used in the studied P-T range but also is accurate enough to be used for prediction of P-V-T data. In addition, IAPWS-95 EOS for H2O shows excellent extrapolation behavior beyond 1.0 GPa and 1273 K. However, for the case of CO2, none of the existing EOS produces data in agreement with the FPMD results. We created new EOS for CO2. The precision of the new EOS is tested by comparison to the calculated P-V-T data, fugacity coefficient of the CO2 fluid derived from high P-T experimental data as well as to the (very scarce) experimental volumetric data in the high P-T range. On the basis of our FPMD data we created a new EOS for H2O-CO2 mixture. The new EOS for the mixture is in reasonable agreement with experimental data.

1 - 5 of 5
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf