Düsseldorf 2007 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 6: Grundlegende Probleme, Theorie

P 6.1: Fachvortrag

Montag, 19. März 2007, 14:35–15:00, 6F

Single particle spectral function and optical properties of dense plasmas — •Carsten Fortmann, Gerd Roepke, and August Wierling — Institut f. Physik, Universität Rostock, 18051 Rostock

Optical properties of plasmas are of great interest for plasma diagnostic purposes. A key quantity is the dielectric function which is determined by the spectral function of the charged particles in the plasma. The spectral function contains all correlations in the system.

In this work, we present a consistent scheme of approximations in order to calculate the electrons spectral function using thermodynamic Green’s functions. By taking into account the dynamical self-energy of the electrons in a self-consistent way, we go beyond the quasiparticle picture and perturbative approaches such as Born approximation. We compare the widely used but inconsistent GW approximation to the GWΓ approximation, in which correlations and exchange are accounted for in a way that sum rules (Ward identities) are fulfilled.

As an application, we present calculations of the inverse bremsstrahlung absorption of moderately coupled plasmas. The results are given in terms of the Gaunt factor, i.e. the correction of Kramer’s result which is based on the quasiparticle approximation. We show in detail, how the account for medium effects via the self-energy modifies the absorption spectrum.