Ensemble Green's function theory for interacting electrons with degenerate ground states

Research output: Contribution to journalArticle


An ensemble Green's function formalism, based on the von Neumann density matrix approach, to calculate one-electron excitation spectra of a many-electron system with degenerate ground states is proposed. A set of iterative equations for the ensemble Green's function and self-energy is derived and a simplest approximation corresponding to an ensemble GW approximation is naturally obtained. The derivation is based on the Schwinger functional derivative technique and does not assume any adiabatic connection between a noninteracting and an interacting ground state.


External organisations
  • Lund University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Condensed Matter Physics
Original languageEnglish
Article number235106
JournalPhysical Review B
Issue number23
Publication statusPublished - 2019
Publication categoryResearch