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A: Fachverband Atomphysik

A 3: Attosecond pulses and high harmonics (jointly with K and Q)

A 3.4: Talk

Monday, March 10, 2008, 17:30–17:45, 3C

Extended Strong-Field Approximation including Collectivity — •Michael Ruggenthaler and Dieter Bauer — Max-Planck-Institut für Kernphysik, Heidelberg

High-order harmonic generation may often be treated within a single active electron picture using the so-called strong-field approximation (SFA) [1] to propagate the initial wave-function. However, if collective phenomena are to be included the standard SFA treatment will not suffice. Although the SFA may be extended via an extra term in the Hamiltonian accounting for the collective behavior of the multi-electron system, there is no straightforward definition of this term.

The problem can be reformulated in time-dependent density-functional theory [2,3] where the so-called Kohn-Sham orbitals are propagated such that total single-particle density is the same as those of the interacting system. The linear response of the density to the external potential gives rise to a time-dependent Hartree-exchange-correlation potential which then can be used within the framework of the extended SFA.

[1] W. Becker et al, Phys. Rev. A 56, 645 (1996)

[2] E. Runge and E. K. U. Gross, Phys. Rev. Lett. 52, 997 (1984)

[3] M. A. L. Marques et al, Time Dependent Density Functional Theory, Lect. Notes Phys. 706 (Springer, Heidelberg, 2006)