Search for dissertations about: "Polaron"

Showing result 1 - 5 of 20 swedish dissertations containing the word Polaron.

  1. 1. Theoretical studies of lattice- and spin-polarons

    University dissertation from Uppsala : Acta Universitatis Upsaliensis

    Author : Nina Bondarenko; Uppsala universitet.; [2018]
    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

  2. 2. A Theoretical Study of Charge Transport in Molecular Crystals

    University dissertation from Linköping : Linköping University Electronic Press

    Author : Elham Mozafari; Linköpings universitet.; Linköpings universitet.; [2013]
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Molecular Crystals; Charge transport; Polaron; Holstein model; Peierls coupling;

    Abstract : The main objective of this thesis is to provide a deeper understanding of the charge transport phenomena occuring in molecular crystals. The focus is on the stability and the dynamics of the polaron as the charge carrier.To achieve this goal, a series of numerical calculations are performed using the semi-emprical "Holstien-Peierls" model. READ MORE

  3. 3. Theoretical Description of the Electron-Lattice Interaction in Molecular and Magnetic Crystals

    University dissertation from Linköping : Linköping University Electronic Press

    Author : Elham Mozafari; Linköpings universitet.; Linköpings universitet.; [2016]
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Molecular crystals; Charge transport; Polaron; Magnetic materials; Paramagnetic state; Molecular dynamics;

    Abstract : Electron-lattice interactions are often considered not to play a major role in material's properties as they are assumed to be small, the second-order effects. However, this study shows the importance of taking these effects into account in the simulations. READ MORE

  4. 4. Electron-lattice dynamics in π-conjugated systems

    University dissertation from Linköping : Linköping University Electronic Press

    Author : Magnus Hultell (Andersson); Linköpings universitet.; Linköpings universitet.; [2008]
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; charge transport; electron-lattice dynamics; polaron; adiabatic transport; electron localization; internal conversion; NATURAL SCIENCES Physics Other physics Computational physics; NATURVETENSKAP Fysik Övrig fysik Beräkningsfysik;

    Abstract : The work presented in this thesis concerns the dynamics in π-conjugated hydrocarbon systems. Due to the molecular bonding structure of these systems there exists a coupling between the electronic system and the phonons of the lattice. READ MORE

  5. 5. Vibrational and Structural Characterisation in Two Perovskite Challenges: A Density Functional Theory Study

    University dissertation from ; Chalmers tekniska högskola; Gothenburg

    Author : Erik Jedvik Granhed; [2019]
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; oxyhydride; phonon; polaron; chemical expansion; materials modelling; anti-ferrodistortive; BaTiO3; BaZrO3; vibrational analysis; density functional theory;

    Abstract : The modelling of perovskites using density functional theory (DFT) can sometimes be a challenge with many different states very close in energy. In particular, the tilting of the inscribed octahedron, as well as the formation of electron polarons, leads to states with energy differences in the meV range. READ MORE