Search for dissertations about: "Polaron"

Showing result 16 - 20 of 30 swedish dissertations containing the word Polaron.

  2. 16. Defects and Impurities in CdTe : An ab Initio Study

    Author : Anna Lindström; Mattias Klintenerg; Susanne Mirbt; Biplab Sanyal; Peter Zahn; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Native defects; Compensation mechanisms; Semiconductor doping; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Abstract : In this thesis defects and impurities in CdTe have been studied with ab initio methods. CdTe is a II-VI semiconductor with many important applications such as γ- and X-ray detectors, solar cells and medical imaging. READ MORE

  4. 17. Model Vertices Beyond the GW Approximation

    Author : Mikael Hindgren; Matematisk fysik; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Matematisk och allmän teoretisk fysik; thermodynamics; statistical physics; gravitation; GW approximation; Electron self energy; Green s function; consistency; local-field corrections; vertex function; conserving approximations; variational energies; Mathematical and general theoretical physics; classical mechanics; relativity; quantum mechanics; klassisk mekanik; kvantmekanik; relativitet; statistisk fysik; termodynamik; Fysicumarkivet A:1997:Hindgren;

    Abstract : We study the effects of local vertex corrections to the self energy of the electron gas. We find that a vertex derived from time-dependent density-functional theory can give accurate self energies without including the explicit time dependence of the exchange-correlation potential provided, however, that a proper decay at large momentum transfer (large q) is built into the vertex function. READ MORE

  5. 18. Properties of Volume Bragg Gratings and Nonlinear Crystals for Laser Engineering

    Author : Staffan Tjörnhammar; Fredrik Laurell; Valdas Pasiskevicius; Takunori Taira; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; volume Bragg grating; VBG; thermal effects; nonlinear optics; KTiOPO4; quasi-phase matching; photochromic damage; grey-tracking; color centers; blue-light induced infrared absorption; BLIIRA; Physics; Fysik;

    Abstract : This thesis focuses on two topics: thermal limitations of volume Bragg gratings (VBGs) employed as laser-cavity mirrors and formation of color centers in KTiOPO4 and its isomorphs.To explore the mechanisms of the thermal limitations of VBGs in high power lasers, I designed and constructed a diode-pumped, solid‑state laser with a VBG as cavity mirror that had a significantly higher absorption than what is typical. READ MORE

  6. 19. Strong Correlation Effects in Bosonic and Fermionic Systems Through an Unbiased Quantum Monte Carlo Approach

    Author : Emil Blomquist; Egor Babaev; Johan Carlström; Barbara Capogrosso Sansone; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Fysik; Physics; Teoretisk fysik; Theoretical Physics;

    Abstract : Strongly interacting many-body quantum systems constitute some of the most challenging problems in physics, and exact analytical solutions are rare. In this thesis, we will investigate the models of two such systems numerically using the unbiased worm-algorithm Monte Carlo method. READ MORE

  7. 20. All-Thin-Film Electrochromic Devices for Optical and Thermal Modulation

    Author : Anna-Lena Larsson; Gunnar A Niklasson; Lars Stenmark; Michael G Hutchins; Uppsala universitet; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering physics; Teknisk fysik; Engineering physics; Teknisk fysik;

    Abstract : The optical properties of electrochromic materials can be changed by application of an electrical voltage. The conventional electrochromic device consists of several thin films of electrochromic materials and layers for electron- and ion conduction. READ MORE