Search for dissertations about: "hubbard-model"

Showing result 1 - 5 of 25 swedish dissertations containing the word hubbard-model.

  2. 1. Correlated materials : models and methods

    Author : Hugo Strand; Göteborgs universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; correlated electrons; Hubbard model; multiband Hubbard model; dynamical mean field theory; exact diagonalization; Landau theory; Mott metal-insulator transition; Gutzwiller method; many-body point group symmetry; ironchalcogenides; Kanamori interaction; Slater-Condon interaction;

    Abstract : This thesis encompass a series of studies on methods and models for electron systems with local interactions, relevant for correlated materials. The first study focus on the canonical model for local correlation, the Hubbard model. READ MORE

  4. 2. Order in Strongly Correlated Quasi-One-Dimensional Systems : Solving Higher-Dimensional Systems Combining Matrix-Product-State Methods and Mean-Field Theory

    Author : Gunnar Bollmark; Adrian Kantian; Annica M. Black-Schaffer; Fabian Heidrich-Meisner; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Superconductivity; strongly correlated systems; matrix-product states; quasi-one-dimensional; Hubbard model; mean-field theory; first-principles calculations.; Fysik; Physics;

    Abstract : Since their discovery the understanding of unconventional superconductors (USCs) has posed a great challenge in condensed matter physics. One central problem, both of theory and experiment, lies in determining the microscopic origin of electron pairing in such systems. READ MORE

  5. 3. Theoretical studies of lattice- and spin-polarons

    Author : Nina Bondarenko; Olle Eriksson; Natalia Skorodumova; Manuel Pereiro; Maria Roser Valenti Vall; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Polaron; Nonlinear Schrödinger Equation; Nonlocality; Solitons; Integrable systems; Quantum field theory low energy ; Electron-phonon interaction; Density functional theory; Electronic structure of atoms and molecules; Spin-polaron; Langevin equation; Transport properties; Hubbard model; Heisenberg lattice; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Abstract : Theoretical studies of lattice- and spin-polarons are presented in this thesis, where the primary tool is ab-initio electronic structure calculations. The studies are performed with employment of a variety of analytical and computational methods. READ MORE

  6. 4. Fermions in two dimensions and exactly solvable models

    Author : Jonas de Woul; Edwin Langmann; Fabian Essler; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Bosonization; Exactly solvable models; Hubbard model; Mean field theory; Quantum field theory; Strongly correlated systems;

    Abstract : This Ph.D. thesis in mathematical physics concerns systems of interacting fermions with strong correlations. For these systems the physical properties can only be described in terms of the collective behavior of the fermions. READ MORE

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

    Author : Miroslav Hopjan; Matematisk fysik; []
    Keywords : 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;

    Abstract : 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. READ MORE