Regensburg 2013 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 33: Poster II

DY 33.57: Poster

Thursday, March 14, 2013, 17:00–19:00, Poster C

Nonequilibrium dynamics of few–electron systems—A comparison of Green functions and reduced density operator theory — •Sebastian Hermanns and Michael Bonitz — ITAP, Christian–Albrechts–Universität Kiel, Leibnizstr. 15, 24098 Kiel

The dynamics of few–electron systems out of equilibrium are among the most interesting but likewise most challenging problems in theoretical physics for the last 50 years. The complexity lies in the fact that, on the one hand, for more than a few particles, direct numerical solutions of the exact equations of motion are mostly not possible due to the exponentially scaling of the problem size. On the other hand, methods relying on statistical averaging can only be applied successfully for much larger particle numbers. In between these two limiting cases, the approximate methods of nonequilibrium Green functions (NEGFs) and the reduced density operator (NEDO) theory have been widely used. To obtain a closed equation of motion for the main quantities, the single-particle NEGFs and NEDOs, one has to find a suitable truncation of respective hierarchies, the Martin–Schwinger– and the BBGKY–hierarchy.

In this contribution, we compare different strategies of truncation, both for NEGFs and NEDOs, with respect to the representability of different time–dependent processes and the compliance with important conservation laws. A main focus lies on the relation between similar approximations for NEGFs and NEDOs^[1].
[1] S. Hermanns, and M. Bonitz, submitted to Jour. Phys. Conf. Ser., arXiv: 1211.6959