Diagrammatic Expansion for Positive Spectral Functions in the Steady-State Limit
| Autor: | Daniel Karlsson, Markku Hyrkäs, Robert van Leeuwen |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
010302 applied physics
Steady state (electronics) Statistical Mechanics (cond-mat.stat-mech) non-equilibrium Green's functions FOS: Physical sciences 02 engineering and technology Positive-definite matrix 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Electronic Optical and Magnetic Materials Diagrammatic reasoning spectral properties Frequency domain Product (mathematics) 0103 physical sciences Applied mathematics Limit (mathematics) Perturbation theory (quantum mechanics) 0210 nano-technology Representation (mathematics) kvanttifysiikka Condensed Matter - Statistical Mechanics Mathematics perturbation theory |
| Popis: | 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 |
| Databáze: | OpenAIRE |
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