Sökning: "Heisenberg model"

Visar resultat 1 - 5 av 25 avhandlingar innehållade orden Heisenberg model.

  1. 1. Renormalization groups and variational states in an interacting 1D quantum model

    Författare :Stefan Rommer; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Heisenberg model; variational states; DMGR;

    Sammanfattning : .... LÄS MER

  3. 2. Anyons and antiferromagnets : two two-dimensional topics

    Författare :Torbjörn Einarsson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; antiferromagnet; two dimension; anyons; fractional statistics; Heisenberg model; torus; nonlinear sigma model; multi-component wavefuntions; spin; Néel phase; disorder; braid group;

    Sammanfattning : .... LÄS MER

  4. 3. Theoretical Studies of Two-Dimensional Magnetism and Chemical Bonding

    Författare :Oleksiy Grechnyev; Olle Eriksson; Alexander Lichtenstein; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; spin Hamiltonians; quantized spin models; Heisenberg model; spin waves; self-consistent spin-wave theory; dipolar interaction; density functional theory; chemical bonding; overlap population; MAX phases; metal hydrides; Fysik; Physics; Fysik;

    Sammanfattning : This thesis is divided into two parts. In the first part we study thermodynamics of the two-dimensional Heisenberg ferromagnet with dipolar interaction. This interaction breaks the conditions of the Mermin-Wagner theorem, resulting in a finite transition temperature. LÄS MER

  5. 4. Strongly Correlated Models in One Dimension from a Density Matrix Renormalization Group Perspective

    Författare :Stefan Rommer; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; matrix product states; impurities; density matrix renormalization group; Heisenberg model; spin chain; DMRG;

    Sammanfattning : The density matrix renormalization group (DMRG) is a numerical method for studying low dimensional strongly correlated models. The study of these models is one of the most active areas of condensed matter physics today and has been spurred not only by the discovery of high temperature superconductivity but also by experiments on new compounds. LÄS MER

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

    Författare :Nina Bondarenko; Olle Eriksson; Natalia Skorodumova; Manuel Pereiro; Maria Roser Valenti Vall; Uppsala universitet; []
    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