Sökning: "random phase approximation"

Visar resultat 1 - 5 av 38 avhandlingar innehållade orden random phase approximation.

  1. 1. Computing attosecond delays in atomic photoionisation : A non-iterative method for many-electron correlation within the Random Phase Approximation with Exchange

    Författare :Anton Ljungdahl; Eva Lindroth; Jon Grumer; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Random phase approximation with exchange; attosecond physics; attosecond delays; teoretisk fysik; Theoretical Physics;

    Sammanfattning : När en atom absorberar fotoner, i växelverkan med tillräckligt högenergetisktljus, så kan en (eller flera) av atomens elektroner ”sparkas ut”. Det resulterar i en positivt laddad jon och en (eller flera) så kallade fotoelektroner. Den här processen är känd som den fotoelektriska effekten, men kallas också för fotojonisering. LÄS MER

  3. 2. Unifying first-principles and model approaches for strongly correlated materials : Interplay between long- and short-range correlations

    Författare :Fredrik Nilsson; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; first-principle methods; strongly correlated materials; GW approximation; cRPA; random-phase approximation; dynamical mean-field theory; GW DMFT; downfolding;

    Sammanfattning : In materials with open 3$d$ and 4$f$ shells the valence electrons are relatively localized around the atoms which leads to large electron-electron correlations. These, so called strongly correlated materials, exhibit many intriguing properties such as high $T_c$ superconductivity, colossal magneto-resistance and heavy fermion behaviour. LÄS MER

  4. 3. Plasmons in Nanostructured Graphene

    Författare :Tobias Wenger; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; linear response theory; surface plasmon-polaritons; Plasmons; surface electrodynamics; plasmonics; graphene; random phase approximation;

    Sammanfattning : Plasmons, collective electron density oscillations, provide physicists with intriguing challenges and possibilities. The inherent many-body properties of the plasmons together with their ability to localize light into small volumes make the plasmons interesting from both a purely theoretical viewpoint and an applications point of view. LÄS MER

  5. 4. First-principles investigations of ordering in binary alloys

    Författare :Moshiour Rahaman; Andrei Ruban; Staunton Julie; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ordering; random; alloys;

    Sammanfattning : The aim of the thesis is to study ordering in binary alloys on the basis of first-principles or {\it ab-initio} techniques employing density functional theory (DFT). The ordering phenomena of materials are of crucial importance for technological applications. LÄS MER

  7. 5. Spectra and Dynamics of Excitations in Long-Range Correlated Structures

    Författare :Lars Kroon; Rolf Riklund; Magnus Johansson; Jeroen Lamb; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; quasicrystals; deterministic aperiodic superlattices; Markov chains; electronic structure and diffusion; elastic vibrations; Fraunhofer diffraction; discrete solitons; phase transitions; Condensed matter physics; Kondenserade materiens fysik;

    Sammanfattning : Vad karaktäriserar en kristall? Svaret på denna till synes enkla fråga blir kanske att det är en anordning av atomer uppradade i periodiska mönster. Så ordnade strukturer kan studeras genom att det uppträder så kallade Braggtoppar i röntgendiffraktionsmönstret. LÄS MER