Sökning: "Time-dependent density functional theory"

Visar resultat 1 - 5 av 41 avhandlingar innehållade orden Time-dependent density functional theory.

  1. 1. 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

  2. 2. Efficient Calculation of Nonlinear Spectroscopic Properties within the Time-Dependent Density Functional Theory Approximation

    Författare :Karan Ahmadzadeh; Patrick Norman; Johannes Neugebauer; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Cubic response; DFT; Response theory; Theoretical Chemistry and Biology; Teoretisk kemi och biologi;

    Sammanfattning : This thesis introduces a novel computational scheme tailored for efficient calculations of nonlinear spectroscopic observables. First, a derivation and implementation of an algorithm designed to harness the linearity of the Fock matrix construction in calculating two-photon absorption cross-sections within the self-consistent field approximation is presented. LÄS MER

  3. 3. Dynamics and Fluctuations in Single-Electron Tunneling Devices

    Författare :Niklas Dittmann; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; quantum dot; time-dependent density-functional theory; perturbation theory; single-electron source;

    Sammanfattning : In recent years, it has been routinely achieved to build nanoscale electronic devices, which generate current pulses carrying only a single elementary charge. Realizations of these single-electron emitters are based on time-dependently driven quantum dots, on single-electron turnstiles built from superconductor/normal-metal hybrid structures, and also on nanosystems employing Lorentzian voltage pulses or surface acoustic waves. LÄS MER

  4. 4. Time-dependent molecular properties in the optical and x-ray regions

    Författare :Ulf Ekström; Patrick Norman; Knut Faegri; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Quantum chemistry; molecular physics; x-ray spectroscopy; relativity; Computational physics; Beräkningsfysik;

    Sammanfattning : Time-dependent molecular properties are important for the experimental characterization of molecular materials. We show how these properties can be calculated, for optical and x-ray frequencies, using novel quantum chemical methods. LÄS MER

  5. 5. Formation and Dynamics of Molecular Excitons and their Fingerprints in Nonlinear Optical Spectroscopy

    Författare :Pär Kjellberg; Kemisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; supraledare; magnetisk resonans; spektroskopi; Physical chemistry; Fysikalisk kemi; Photochemistry; Fotokemi; Kondenserade materiens egenskaper:elektronstruktur; magnetiska och optiska ; egenskaper elektriska; supraconductors; magnetic resonance; relaxation; spectroscopy; Fysik; Chemistry; Kemi; Condensed matter:electronic structure; electrical; Physics; Redfield relaxation theory ; Inhomogeneous broadening ; Time-dependent density functional theory ; Conjugated polymers ; Three-pulse photon echo ; Molecular excitons ; magnetic and optical properties; Nonlinear spectroscopy ;

    Sammanfattning : An efficient transfer of energy in molecular systems has proven to be of fundamental importance both in nature and industrial applications. The ability of molecules to work together forming collective excitations, so-called excitons, plays a key role in for example the extraordinary fast energy transfer involved in the first steps of photosynthesis. LÄS MER