Diagrammatic expansion for positive density-response spectra: Application to the electron gas
Diagrammatic expansion for positive density-response spectra: Application to the electron gas
In a recent paper [Phys. Rev. B 90, 115134 (2014)] we put forward a diagrammatic expansion for the self-energy which guarantees the positivity of the spectral function. In this work we extend the theory to the density-response function. We write the generic diagram for the density-response spectrum as the sum …