Essays about: "GW approximation"

Found 4 essays containing the words GW approximation.

  1. 1. Ensemble Green's Function Theory for Interacting Electrons with Degenerate Ground States

    University essay from Lunds universitet/Matematisk fysik; Lunds universitet/Fysiska institutionen

    Author : Erik Linnér; [2019]
    Keywords : Green s function; Degeneracy; Density matrix; Ensemble; GW; Zero-temperature; Finite-temperature; Hubbard model; Two-dimensional harmonic oscillator; Ising model; Hydrogen-like model; Physics and Astronomy;

    Abstract : An ensemble Green's function theory for many-electron systems with degenerate ground states, based on the von Neumann density matrix formalism, is proposed. The formalism is constructed without an assumption of an adiabatic connection. An ensemble analogue of Hedin's equations and the GW Approximation (GWA) is constructed. READ MORE

  3. 2. The self-screening correction to RPA and GW – A model and ab initio study

    University essay from Lunds universitet/Matematisk fysik; Lunds universitet/Fysiska institutionen

    Author : Viktor Christiansson; [2019]
    Keywords : GW approximation; GWA; Random-Phase-Approximation; RPA; Self-screening; Self-screening correction; Beyond RPA; Beyond GW; Physics and Astronomy;

    Abstract : The self-screening error in the GW approximation is studied by applying correction schemes beyond the random-phase approximation in model and ab inito calculations. Two model systems in the form of Hubbard dimers, with one and two orbitals per site respectively, are considered. READ MORE

  4. 3. Combining the GW Approximation with the Hubbard I Approximation for strongly correlated materials

    University essay from Lunds universitet/Matematisk fysik; Lunds universitet/Fysiska institutionen

    Author : Torsten Strunck; [2019]
    Keywords : GWA; GW Approximation; HIA; Hubbard I Approximation; Hubbard-I Approximation; Hubbard model; DMFT; Dynamical Mean Field Theory; strongly correlated materials; electron correlations; solid state physics; Physics and Astronomy;

    Abstract : In this thesis, the GW approximation (GWA, Green's function G times screened interaction W) and the Hubbard I approximation (HIA) are combined in a non-self-consistent one-shot calculation to determine the electronic structure of a one-dimensional strongly-correlated model. The scheme was chosen to incorporate both screening effects through the GWA and strong on-site correlations through the atomic HIA. READ MORE

  5. 4. Investigating the GW self-energy of the homogeneous electron gas in real space

    University essay from Lunds universitet/Matematisk fysik; Lunds universitet/Fysiska institutionen

    Author : Zhen Zhao; [2018]
    Keywords : GW method; self energy; screened-exchange; Coulomb-hole; Physics and Astronomy;

    Abstract : The real space behavior of the GW self-energy in the electron gas model was investigated in this thesis work. The self-energy is naturally decomposed into the screened-exchange and the Coulomb-hole components. READ MORE