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

Abstract

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.

arXiv comment6 pages, 2 figures

References in corpus (6)

• The GW method
• Fractionalized excitations in the spin liquid state of a kagomé lattice antiferromagnet
• Coupling of excitons and defect states in boron-nitride nanostructures
• Ensemble density functional theory of the fractional quantum Hall effect
• First-principles calculations of the electronic structure of open-shell condensed matter systems
• The many-body Green function of degenerate systems

Cited by in corpus (2)

• Connections between many-body perturbation and coupled-cluster theories
• Can $GW$ Handle Multireference Systems?