Hannover 2010 – scientific programme

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A: Fachverband Atomphysik

A 8: Poster I

A 8.18: Poster

Tuesday, March 9, 2010, 16:30–19:00, Lichthof

Efficient grid-based nonequilibrium Green’s function calculations: II. Code parallelization and resolution of time-dependent atomic features — •Karsten Balzer and Michael Bonitz — ITAP, Christian-Albrechts-Universität Kiel, Leibnizstr. 15, 24098 Kiel

The real-time propagation of the nonequilibrium Green’s function (NEGF) solving the two-time Schwinger/Keldysh/Kadanoff-Baym equations generally involves very large computational resources and, hence, reveals limited capabilities. For this reason, using the finite-element discrete variable representation [1-3], we develop a parallel code which gets along with minumum random access memory (RAM) at acceptable inter-node communication. The resulting program is ready for large cluster computation and should enable enhanced applicability of NEGFs in atomic problems.

As first benchmarks, we compute, in second Born approximation, the nonequilibrium behavior of the one-dimensional helium atom starting from the self-consistent (correlated) ground-state state [3]. From the time-propagation, we extract the dipole-strength and discuss one- and two-electron excitations. Also, the results are compared to solutions of the two-particle time-dependent Schrödinger equation.

[1] T.N. Rescigno, and C.W. McCurdy, Phys. Rev. A 62, 032706 (2000). [2] B.I. Schneider, L.A. Collins, and S.X. Hu, Phys. Rev. E 73, 036708 (2006). [3] K. Balzer, S. Bauch, and M. Bonitz, arXiv:0910.5458, submitted to Phys. Rev. A (2009).