Frankfurt 2006 – scientific programme

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A: Atomphysik

A 18: Wechselwirkung mit starken Laserpulsen II: Ionisation

A 18.4: Talk

Thursday, March 16, 2006, 15:00–15:15, H6

A new adiabatic density-functional treatment of ionisation in Helium — •Astrid S. de Wijn¹, Stephan Kümmel², and Manfred Lein³ — ¹MPIPKS Dresden — ²University of Bayreuth — ³MPI für Kernphysik Heidelberg

Past investigations have shown that present day time-dependent density functionals do not properly describe the double ionisation of Helium. Recently, it has been suggested that this problem may be related to the absence of a derivative discontinuity in these functionals [1]. We introduce a new, adiabatic time-dependent density-functional which includes the exact ground-state correlation potential for a fractional particle number that corresponds to the present number of bound electrons. The other terms in the Kohn-Sham potential are calculated exactly. For one-dimensional Helium with a softened Coulomb potential, we compare this No-dqexactNo-dq adiabatic approximation to fully exact results as well as results from Hartree-Fock calculations. We find that the adiabatic approximation reproduces the knee structure in the laser-intensity dependence of the double-ionisation probability.

[1]M. Lein and S. Kümmel, Phys. Rev. Lett. 94, 143003 (2005).