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Visar resultat 6 - 10 av 25 avhandlingar som matchar ovanstående sökkriterier.

  1. 6. Theoretical Studies of Atomic Structure, Radiative Transitions and Interference Effects

    Författare :Martin Andersson; Fysiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Naturvetenskap; Natural science; Computational physics; Zeeman; Transition rate; Lifetime; Hyperfine structure; Interference; Atomic structure;

    Sammanfattning : Theoretical calculations concerning the advanced understanding of atomic structure and transitions has been performed for some atomic systems. The importance of different types of correlation depending on system has been investigated both using relativistic and non-relativistic quantum mechanics. LÄS MER

  3. 7. Towards a relativistically covariant many-body perturbation theory - With numerical implementation to helium-like ions

    Författare :Daniel Hedendahl; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; many-body perturbation theory; bound state QED; helium-like ions; Green s operator; covariant evolution operator; combined effects of QED and correlation; atomic structure calculations;

    Sammanfattning : The experimental results for simple atomic systems have become more and more accurate and in order to keep up with the experimental achievements the theoretical procedures have to be refined. Recent accurate experimental results obtained for helium-like ions in the low- and moderate-Z regions proclaim the importance of theoretical calculations that combines relativistic, QED and electron correlation effects. LÄS MER

  4. 8. Interaction of atomic ions with electrons : Recombination rate coefficients for C1+, F5+, Ne5+, S14+,S15+

    Författare :Sultan Mahmood; Reinhold Schuch; Christoph Biedermann; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; fysik; Physics;

    Sammanfattning : This thesis concentrates on electron-ion interaction studies, in particular focusing on dielectronic recombination (DR) of highly charged ions relevant to astrophysics and plasma physics. The measurements were performed at the Stockholm Refrigerated Electron Beam Ion Trap (R-EBIT) and at the CRYRING heavy-ion storage ring. LÄS MER

  5. 9. Computational Atomic Structure: Applications to Astrophysics and Nuclear Structure

    Författare :Asimina Papoulia; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : This thesis deals with the modelling of atoms and ions. In heavy systems, where the effect of the nuclear size must be considered, a fully relativistic treatment based on the Dirac-Coulomb Hamiltonian is needed. LÄS MER

  7. 10. Atomistic spin dynamics and relativistic effects in chiral nanomagnets

    Författare :Konstantinos Koumpouras; Anders Bergman; Olle Eriksson; Manuel Pereiro; Elena Vedmenenko; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : In this thesis, studies based on magnetization dynamics on atomic length scales are presented for a number of magnetic systems, where Dzyaloshinskii-Moriya (DM) interaction is present. First-principle methods, based on density functional theory (DFT), have been used to study the pairwise magnetic interactions, such as Heisenberg exchange and DM interaction, which are the crucial parameters for the helimagnetic systems. LÄS MER