Kiel 2011 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 18: Poster: Theorie/Simulation dichter und stark gekoppelter Plasmen

P 18.9: Poster

Mittwoch, 30. März 2011, 16:30–18:30, Foyer

Time propagation of the Nonequilibrium Green’s function using the generalized Kadanoff-Baym ansatz — •Sebastian Hermanns, Karsten Balzer, and Michael Bonitz — ITAP, Christian-Albrechts-Universität Kiel, Leibnitzstr. 15, 24098 Kiel

For the description of many-particle systems the Green’s function method has become widely used in the last decade. The equations of motion for this quantity are the Keldysh-Kadanoff-Baym equations (KKBE). The simplest approximation that includes correlation effects is the second Born approximation. However, as the two-time structure leads to quadratic scaling of the memory cost with simulation length, only short term dynamics can be computed. By introducing the generalized Kadanoff-Baym ansatz (GKBA) ansatz into the KKBE, the two-particle Green’s function is reconstructed from its value on the time diagonal. This leads to a linear scaling of the memory cost with simulation length which makes longer time evolution possible.

In this contribution, we apply the GKBA to the time evolution of model atoms such as helium in one dimension [1,2]. With results for time dependent spatial and spectral properties the GKBA is compared to two-time 2nd Born-, Hartree-Fock-calculations as well as to the exact solution of the time-dependent Schrödinger equation. A special focus thereby lies on how well 2-electron excitations, which play an important role for the correlated electron dynamics, are represented in GKBA calculations.

[1,2] K. Balzer, S. Bauch, and M. Bonitz, Phys. Rev. A 81, 022510 (2010) and 82, 033427 (2010).