Sökning: "GW"

Visar resultat 1 - 5 av 50 avhandlingar innehållade ordet GW.

  1. 1. Atomistic modelling of functional solid oxides for industrial applications : Density Functional Theory, hybrid functional and GW-based studies

    Författare :Cecilia Århammar; Rajeev Ahuja; Steven Louie; KTH; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; density functional theory; oxides; GW; Condensed matter physics; Kondenserade materiens fysik; Magnetism; Magnetism; Defects and diffusion; Defekter och diffusion;

    Sammanfattning : In this Thesis a set of functional solid oxides for industrial applications have been addressed by first principles and thermodynamical modelling. More specificially, measurable quantities such as Gibbs free energy, geometry and electronic structure have been calculated and compared when possible with experimental data. LÄS MER

  2. 2. Model Vertices Beyond the GW Approximation

    Författare :Mikael Hindgren; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; 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;

    Sammanfattning : 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. LÄS MER

  3. 3. Electronic Structure and Optical Properties of Solar Energy Materials

    Författare :Baochang Wang; Natalia Skorodumova; Silvana Botti; KTH; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; GW; Bethe-Salpeter equation; Kinetic Monte Carlo; Density Functional Theory; Materials Science and Engineering; Teknisk materialvetenskap;

    Sammanfattning : In this thesis, we have studied the electronic and optical properties of solar energy m-terials. The studies are performed in the framework of density functional theory (DFT), GW, Bethe-Salpeter equation (BSE) approaches and Kinetic Monte Carlo (KMC). We present four sets of results. LÄS MER

  4. 4. Periodized Thermal Greens Functions and Applications

    Författare :Andro Sabashvili; Göteborgs universitet; Göteborgs universitet; Gothenburg University; []
    Nyckelord :condensed matter physics; Greens function; graphene; DMFT; RPA; GW;

    Sammanfattning : This work describes a new formalism for Fermionic thermal Greens functions that are discretized in imaginary time. The discretization makes the thermal Greens function periodic in imaginary (Matsubara) frequency space and requires a generalisation of the Dyson equation and Luttinger-Ward-Baym-Kadanoff functional. LÄS MER

  5. 5. 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; 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