Search for dissertations about: "time-dependent density-functional theory"

Showing result 1 - 5 of 39 swedish dissertations containing the words time-dependent density-functional theory.

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

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

   Abstract : 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. READ MORE

4. 2. Time-Dependent Many-Body Perturbation Theory: Possibilities and Limitations

   Author : Marc Puig von Friesen; Matematisk fysik; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Many-body perturbation theory; Correlation functions; Hubbard model; Non-equilibrium Green s functions; Fysicumarkivet A:2011:Puig von Friesen;

   Abstract : 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. READ MORE

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

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

   Abstract : 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. READ MORE

6. 4. Application and development of quantum chemical methods. Density functional theory and valence bond theory

   Author : Fuming Ying; Olav Vahtras; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Theoretical chemistry; Teoretisk kemi;

   Abstract : This thesis deals with two disjoint subdiciplines of quantum chemistry.  One isthe most used electronic structure method today, density functional theory(DFT), and the other one of the least used electronic structure methods,valence bond theory (VB). READ MORE

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

   Author : Pär Kjellberg; Kemisk fysik; []
   Keywords : 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 ;

   Abstract : 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. READ MORE