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DPG

Berlin 2001 – wissenschaftliches Programm

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P: Plasmaphysik

P 5: Theory

P 5.3: Vortrag

Mittwoch, 4. April 2001, 16:30–16:45, 2053

Response function for interacting quantum liquids — •Klaus Morawetz1 and Uwe Fuhrmann21Max-Planck-Institute for the Physics of Complex Systems, Noethnitzer Str. 38, 01187 Dresden, Germany — 2Fachbereich Physik, University Rostock, D-18055 Rostock,Germany

Linearizing the appropriate kinetic equation we derive general response functions including selfconsistent mean fields or density functionals and collisional dissipative contributions. The latter ones are considered in relaxation time approximation conserving successively different balance equations. We find that momentum conservation leads exactly to the local field corrections for both cases respecting only density conservation and respecting density and energy conservation. This rewriting simplifies the formulae dramatically. We discuss the higher order sum rules and small wave vector expansion and find that the response function shows a high frequency dependence of ω−5 which allows to fulfill higher order sum rules. The presented results are applicable to finite temperature response of interacting quantum systems with quasiparticle or mean field energies. We present results for collective modes like the plasmon in plasma systems and the giant resonance in nuclei. The collisions lead in general to an enhanced damping of collective modes. If the collision frequency is close to the frequency of the collective mode, resonance occurs and the collective mode is enhanced showing a collisional narrowing.
Phys. Rev. E 62 (2000) 4382: Momentum conservation and local field corrections for the response of interacting Fermi gases K. Morawetz, Uwe Fuhrmann Phys. Rev. E 61 (2000) 2272-2280: General response function for interacting quantum liquids, K. Morawetz, U. Fuhrmann

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