Search for dissertations about: "Mean-field approximation"

Showing result 11 - 15 of 25 swedish dissertations containing the words Mean-field approximation.

  2. 11. Cohesive and Spectroscopic properties of the Lanthanides within the Hubbard I Approximation

    Author : Inka Laura Marie Locht; Igor Di Marco; Olle Eriksson; Annalisa Fasolino; Mikhail I. Katsnelson; Tim Wehling; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Lantanides; rare earths; cohesive properties; volume; bulk modulus; magnetism; magnetic properties; photoemission spectroscopy; XPS; BIS; Hubbard I Approximation; DMFT; DFT; RSPt; Full Potential Linear Muffin-tin orbitals; 4f electrons; localization; bonding; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Abstract : We describe the rare-earth elements using the Hubbard I approximation. We show that the theory reproduces the cohesive properties, like the volume and bulk modulus, and we find an excellent agreement between theory and experiment for the (inverse) photo emission spectra of the valence band. READ MORE

  4. 12. Periodized Thermal Greens Functions and Applications

    Author : Andro Sabashvili; Göteborgs universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; condensed matter physics; Greens function; graphene; DMFT; RPA; GW;

    Abstract : This work describes a new formalism for Fermionic thermal Greens functions that are discretized in imaginary time. The discretization makes the thermal Greens function periodic in imaginary (Matsubara) frequency space and requires a generalisation of the Dyson equation and Luttinger-Ward-Baym-Kadanoff functional. READ MORE

  5. 13. Quest for quantum signatures in Axion Dark Matter and Gravity

    Author : Vasileios Fragkos; Igor Pikovski; Ingemar Bengtsson; Stockholms universitet; []
    Keywords : Axion Dark Matter; Gravity; Quantum mechanics; Theoretical Physics; teoretisk fysik;

    Abstract : This licentiate thesis in theoretical physics focuses on the existence of quantum features in physical systems such as axion dark matter and gravity. Our focus is mostly on effects which appear at low energies, a regime in which our models can be confronted with current experiments or within the foreseeable future. READ MORE

  6. 14. Calculation of magnetism and its crystal structure dependence

    Author : Peter James; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Physics; Fysik; Physics; Fysik; fysik; Physics;

    Abstract : The subject of the present thesis is a theoretical investigation of magnetism and its crystal structure dependence by means of electronic-structure calculations from first principles. The theoretical treatment is based on density functional theory and the so called linear muffin-tin orbital method is used in its full-potential version as well as in an atomic sphere approximation. READ MORE

  7. 15. First-principles Studies of Local Structure Effects in Magnetic Materials

    Author : Marcio Costa; Anders Bergman; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; magnetic anisotropy; DMFT; magnetism; DFT; Materialvetenskap; Materials Science;

    Abstract : This thesis focus on the magnetic behavior, from single atoms to bulk materials. The materials considered in this thesis have been studied by computational methods based on ab initio theory, density functional theory (DFT), including treatment of the spin-orbit coupling, non-collinear magnetism, and methods capable of treating discorded systems. READ MORE