Diagrammatic Expansion for Positive Spectral Functions in the Steady-State Limit
arXiv:1905.04290 · doi:10.1002/pssb.201800615
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.
arXiv comment7 pages, 4 figures, KBEt2 2019
References in corpus (6)
- Conserving GW scheme for nonequilibrium quantum transport in molecular contacts
- Kadanoff-Baym approach to quantum transport through interacting nanoscale systems: From the transient to the steady-state regime
- Diagrammatic expansion for positive spectral functions beyond GW: Application to vertex corrections in the electron gas
- Hamiltonian-based impurity solver for nonequilibrium dynamical mean-field theory
- Diagrammatic expansion for positive density-response spectra: Application to the electron gas
- Lehmann representation of the nonequilibrium self-energy