Diagrammatic Expansion for Positive Spectral Functions in the Steady-State Limit

Abstract

Recently, a method was presented for constructing self-energies within many-body perturbation theory that are guaranteed to produce a positive spectral function for equilibrium systems, by representing the self-energy as a product of half-diagrams on the forward and backward branches of the Keldysh contour. We derive an alternative half-diagram representation that is based on products of retarded diagrams. Our approach extends the method to systems out of equilibrium. When a steady-state limit exists, we show that our approach yields a positive definite spectral function in the frequency domain.

7 pages, 4 figures, KBEt2 2019

References in corpus (3)

• Conserving GW scheme for nonequilibrium quantum transport in molecular contacts
• Diagrammatic expansion for positive spectral functions beyond GW: Application to vertex corrections in the electron gas
• Diagrammatic expansion for positive density-response spectra: Application to the electron gas

Cited by in corpus (1)

• Dynamically screened vertex correction to $GW$