Towards a Time-Dependent Density-Functional Description of Multiple Multiphoton-Ionization of Helium in Strong Laser Fields

In this work we address the problem of multiple ionization of atoms in strong laser fields (in the infrared and visible range). To this end we numerically solve the full, three-dimensional time-dependent Kohn-Sham equations for a Helium atom in a strong (780nm) laser field. Explicit density functionals for the calculation of ionization probabilities are developed. From the results, we will draw conclusions about the role of electronic correlation in the ionization dynamics and about the validity of present-day exchange-correlation potentials.