4 Matching Annotations
  1. May 2019
    1. However, it is still often stated that the other orbital energies have no physical meaning, and that it is a pity that nothing like Koopmans' theorem to give meaning to the other occupied orbital energies exists. The truth could not be more different: it has been established22–25 that the KS orbital energies of the valence levels in molecules approximate the experimental ionization energies much more closely (typically at 0.1 eV level) than the Hartree–Fock orbital energies do (difference with IPs typically ∼1 eV).

      This is really one of the more spicy takes here. KS orbitals having no physical interpretation is often heard in the community, and here is a list of references and evidence that they do have physical significance.

  2. Oct 2018
    1. More details on the Green function theory may be found in standard text books on many-bodytheory (e.g. Nozi`eres 1964, Fetter and Walecka 1971, Inkson 1984, Mahan 1990) and in the reviewarticle by Hedin and Lundqvist (1969).

      Really important references, esp the Fetter and Walecka many body quantum book.

    2. Calculations of Σ are unfortunately very difficult even for the electrongas. We must resort to approximations and this review describes theGWapproximation (GWA)(Hedin 1965a) which is the simplest working approximation beyond the HFA that takes screeninginto account.

      This is a good explanation of what GW really does. It calculates the self energy.

    3. Recent reviews on DFT may be found in Jones and Gunnarsson (1989) and Dreizler andGross (1990)

      This is before the PAW method came along (Blochl '94), so probably nothing method-specific.