Sökning: "Heisenberg lattice"

Visar resultat 1 - 5 av 10 avhandlingar innehållade orden Heisenberg lattice.

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

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Nina Bondarenko; Uppsala universitet.; [2018]
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER

  2. 2. Simulation of Core-Level Spectra of H-bonded Systems

    Detta är en avhandling från Stockholm : Department of Physics, Stockholm University

    Författare :Iurii Zhovtobriukh; Stockholms universitet.; [2019]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; water; x-ray absorption; non-resonant x-ray emission; damped linear response theory; time-dependent density functional theory; semi-classical approximation to Kramers-Heisenberg formula; Reverse Monte-Carlo; kemisk fysik; Chemical Physics;

    Sammanfattning : The thesis consists of three related projects where attempts have been made to simulate X-Ray Absorption (XAS) spectra of water and hexagonal ice, static non-resonant X-ray Emission (XES) spectrum of water and to apply the semi-classical approximation to Kramers-Heisenberg formula (SCKH) formalism to calculate the non-resonant XES spectrum of water and methanol. The first project is devoted to an investigation of the performance of damped response theory in combination with the DFT electronic structure method (CPP-DFT) in XAS spectrum simulations of liquid water. LÄS MER

  3. 3. Numerical studies of spin chains and cold atoms in optical lattices

    Detta är en avhandling från Stockholm : KTH

    Författare :Sara Bergkvist Sylvan; KTH.; [2007]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Teoretisk Fysik; Kondenserade materiens teori; NATURAL SCIENCES Physics Condensed matter physics; NATURVETENSKAP Fysik Kondenserade materiens fysik;

    Sammanfattning : An important, but also difficult, research field in condensed matter physics is that of strongly correlated systems. This thesis considers two topics in this field.The first topic is disorder and frustration in spin models. The introduction of disorder into quantum spin chains creates a complex problem. LÄS MER

  4. 4. Structural and magnetic disorder in crystalline materials a first principles study

    Detta är en avhandling från Linköping : Linköping University Electronic Press

    Författare :Davide Gambino; Linköpings universitet.; Linköpings universitet.; [2019]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : Disorder in crystalline materials can take different forms and originate from different sources. In particular, temperature introduces disorder in any kind of material. LÄS MER

  5. 5. Trends in Magnetism From Strong Correlations to “-onics” Technology

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Dmitry Yudin; Uppsala universitet.; [2015]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Strongly interacting electron systems; Spin dynamics; Topological matter; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : Despite of enormous progress in experimental nanophysics theoretical studies of low-dimensional electron systems still remains a challenging task. Indeed, most of the structures are strongly correlated, so that an effective perturbative treatment is impossible due to the lack of a small parameter. LÄS MER