Sökning: "first-principles"

Visar resultat 1 - 5 av 34 uppsatser innehållade ordet first-principles.

  1. 1. Cosmological Horizons and the Unruh Effect

    L3-uppsats, Uppsala universitet/Teoretisk fysik

    Författare :Niklas Engelhardt Önne; [2023]
    Nyckelord :Unruh effect; quantum scalar fields; Bogoliubov transformations; accelerated observers; Minkowski spacetime; cosmological horizons; Rindler observers; special relativity; QFT; Unruh-effekten; skalära kvantfält; Bogoliubov-transformationer; accelererande referenssystem; Minkowski rumtid; kosmologiska horisonter; Rindlerobservatörer; speciell relativitetsteori; QFT;

    Sammanfattning : The black hole information paradox, which states that the evaporation of black holes due to Hawking radiation results in a violation of the conservation of quantum information, is arguably one of the most fundamental problems in all of modern physics. Through the equivalence principle, the essence of the problem can be understood and studied in the context of much simpler flat spacetime (described by the theory of special relativity); in this context the Hawking radiation takes the form of the so-called Unruh effect, a thermal effect in the vacuum of a Minkowski quantum field theory that can be measured by accelerated observers. LÄS MER

  3. 2. First principles investigation of the thermal conductivity of Zr, ZrC, and ZrN

    Master-uppsats, KTH/Fysik

    Författare :Daniel Karlsson; [2023]
    Nyckelord :Electron-phonon interaction; Density functional theory; Boltzmann transport equation; first-principles; thermal conductivity; electrical resistivity; Abinit; Phono3py; Elektron-fononväxelverkan; täthetsfunktionalteori; Boltzmanns transportekvation; värmeledningsförmåga; elektrisk resistivitet; Abinit; Phono3py;

    Sammanfattning : The thermal conductivity and electrical resistivity of Zr, ZrC, and ZrN were calculated using first-principles density functional theory (DFT) and the Boltzmann transport equation. The electron-phonon scattering was modeled via the self-energy relaxation time approximation (SERTA), and the phonon-phonon scattering via the analogous single-mode relaxation time approximation (SMRTA). LÄS MER

  4. 3. How to Rise from Ashes : A Comprehensive Guide to Finally Understand Canonical Quantization and Build Quantum Mechanics from Scratch

    L3-uppsats, Uppsala universitet/Materialteori; Uppsala universitet/Avdelningen för teoretisk filosofi

    Författare :Karl Herlin; [2022]
    Nyckelord :Quantum mechanics; History of quantum mechanics; Canonical Quantization; double-slit experiment; The Photoelectric Effect; Compton Scattering; Matter Waves; Bohr’s Atomic Model; Old Quantum Theory; Heisenberg-Born-Jordan Matrix Mechanics; Schrodinger’s Quantum Wave Mechanics; equations of motion;

    Sammanfattning : In this review essay, we account for the historical development of canonical quantization. By a detailed review of The Ultraviolet Catastrophe, The Photoelectric Effect, Compton Scattering, Matter Waves and Bohr's Atomic Model we learn about Old Quantum Theory. LÄS MER

  5. 4. Birefringence: Effects and Implications on In-Ice Radio Detection of High-Energy Neutrinos

    Master-uppsats, Uppsala universitet/Högenergifysik

    Författare :Nils Heyer; [2022]
    Nyckelord :Birefringence; Cosmic Neutrinos; In-ice radio propagation;

    Sammanfattning : The detection of high-energy neutrinos in the EeV range requires new detection techniques to cope with the small expected flux. The radio detection method, utilizing Askaryan emission, can be used to detect these neutrinos in polar ice. LÄS MER

  7. 5. Photophysics of the polymer acceptor PF5-Y5 in organic photovoltaics : A first principles theory based study

    Master-uppsats, Karlstads universitet/Institutionen för ingenjörsvetenskap och fysik (from 2013)

    Författare :Anton Almén; [2022]
    Nyckelord :PF5-Y5; Non-fullerene-acceptor; NFA; polymer; fundamental; optical; gap; oxidation; reduction; exciton; binding; energy; oligomer; length; PF5-Y5; Non-fullerene-acceptor; NFA; polymer; fundamentalt; optiskt; gap; oxidation; reduktion; exciton; binding; energi; oligomerlängd;

    Sammanfattning : Non-fullerene Acceptors (NFAs) have gathered a great deal of interest for use inorganic photovoltaics (OPVs) due to recent breakthroughs in their power conversion efficiency and other advantages they offer over their Fullerene-based counterparts. In this work, a new promising non-fullerene polymer acceptor, PF5-Y5, have been studied using density functional theory and time-dependent density functional theory; and the effects that oligomer length, geometry relaxation and exchange-correlation interaction has on the exciton binding energies (the difference between optical and fundamental energy gaps) have been investigated. LÄS MER