Sökning: "electron correlation"

Visar resultat 26 - 30 av 276 avhandlingar innehållade orden electron correlation.

  1. 26. Theoretical Atomic Spectroscopy of Earthbound and Stellar Plasma

    Författare :Jon Grumer; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; atomstruktur; atomära processer; elektronkorrelation; plasmaspektroskopi; magnetfält; hyperfinstruktur; solkoronan; rymdväder; förekomst av grundämnen i stjärnor; datorsimuleringar; Zeemaneffekt; relativistiska effekter; atomic structure; atomic processes; computer simulation; electron correlation; relativistic atomic theory; plasma spectroscopy; Zeeman effect; magnetic fields; hyperfine structure; solar corona; space weather; stellar abundances; Fysicumarkivet A:2016:Grumer;

    Sammanfattning : Motivated by spectroscopic analysis of astrophysical and laboratory plasma, this thesis concerns the fundamental structure and spectral properties of atoms and their ions. The multiconfiguration Dirac-Hartree-Fock (MCDHF) method is used to predict the emission or absorption of radiation, by atomic systems in general, and of heavy and highly charged ions in particular. LÄS MER

  3. 27. Ultra-fast dynamics in atoms and molecules during photoionization: from attoseconds to femtoseconds

    Författare :Erik Månsson; Synkrotronljusfysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; photoelectron spectroscopy; momentum imaging; coincident detection; correlation; direct double ionization; Born–Oppenheimer approximation; high harmonics; synchrotron radiation; Fysicumarkivet A:2014:Månsson;

    Sammanfattning : Treating the correlated behaviour of multiple particles is challenging for both theory and experiment. This thesis reports on a variety of experimental investigations aiming to advance the understanding of fundamental processes in atoms and molecules: double ionization, isomerization and dissociation. LÄS MER

  4. 28. Transition Properties of f-electrons in Rare-earth Optical Materials

    Författare :Daniel Åberg; Börje Johansson; Sverker Edvardsson; Lidia Smentek; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; rare-earth ions; oscillator strengths; correlation; crystal field; f-electrons; Fysik; Physics; Fysik;

    Sammanfattning : The main purpose of this thesis is to theoretically study energy levels and intra-electronic transition intensities for various f-electron systems. The f-f electronic dipole transitions are parity-forbidden for a free ion but become non-zero when the ion is subject to a crystal-field. LÄS MER

  5. 29. Correlated Electronic Structure of Materials : Development and Application of Dynamical Mean Field Theory

    Författare :Patrik Thunström; Olle Eriksson; Alexander Lichtenstein; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; DFT; DMFT; correlation; entanglement; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : This thesis is dedicated to the development, implementation and application of a combination of Density Functional Theory and Dynamical Mean Field Theory. The resulting program is shown through several examples to be a powerful and flexible tool for calculating the electronic structure of strongly correlated materials. LÄS MER

  7. 30. New Approaches to Large-Scale Electronic Structure Calculations

    Författare :Francesco Aquilante; Beräkningskemi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Theoretical chemistry; orbital localization; electron correlation; analytic gradients; Cholesky decomposition; density fitting; quantum chemistry; Teoretisk kemi; kvantkemi;

    Sammanfattning : Recent years have witnessed a growing interest of the scientific community for the use of ab initio and density functional theory methods in theoretical studies of molecules containing many atoms. However, the `scaling wall' of some of the most accurate of such methods is often an obstacle for their applicability to systems of real-life interest, e. LÄS MER