Sökning: "Hubbard I Approximation"

Visar resultat 1 - 5 av 12 avhandlingar innehållade orden Hubbard I Approximation.

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

    Författare :Inka Laura Marie Locht; Igor Di Marco; Olle Eriksson; Annalisa Fasolino; Mikhail I. Katsnelson; Tim Wehling; Uppsala universitet; []
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER

  3. 2. Theoretical methods for the electronic structure and magnetism of strongly correlated materials

    Författare :Inka L. M. Locht; Igor Di Marco; Silke Biermann; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; dynamical mean field theory DMFT ; Hubbard I approximation; strongly correlated systems; rare earths; lanthanides; photoemission spectra; ultrafast magnetization dynamics; analytic continuation; Padé approximant method; two-particle Green s functions; linear muffin tin orbitals LMTO ; density functional theory DFT ; cerium; stacking fault energy.; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : In this work we study the interesting physics of the rare earths, and the microscopic state after ultrafast magnetization dynamics in iron. Moreover, this work covers the development, examination and application of several methods used in solid state physics. The first and the last part are related to strongly correlated electrons. LÄS MER

  4. 3. Time-Dependent Many-Body Perturbation Theory: Possibilities and Limitations

    Författare :Marc Puig von Friesen; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Many-body perturbation theory; Correlation functions; Hubbard model; Non-equilibrium Green s functions; Fysicumarkivet A:2011:Puig von Friesen;

    Sammanfattning : This dissertation investigates the possibilities and limitations of time-dependent many-body perturbation theory by studying small Hubbard clusters for which the exact solution is available. The first part of the thesis is comprised of a short introduction to the concepts and methodologies used. LÄS MER

  5. 4. Theoretical Developments for the Real-Time Description and Control of Nanoscale Systems

    Författare :Miroslav Hopjan; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Green’s Function; DFT; TDDFT; Hubbard Model; Many-Body Perturbation Theory; Strongly Correlated Systems; Quantum Transport; Disorder; Ehrenfest Dynamics; Electronic Friction; Exact Diagonalization; Periodic Anderson Model; Fysicumarkivet A:2018:Hopjan;

    Sammanfattning : In this thesis we focus on improvements of the description of the electron-electron correlation effects in nonequilibrium nanosystems. We mainly focus on developments of two nonequilibrium methods, namely the formalism of Nonequilibrium Green’s Function and Time Dependent Density Functional Theory and we explore the possibility to improve existing approximations in these theories. LÄS MER

  7. 5. 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