Density-functional approach to strong-field electron dynamics of the helium atom

Time-dependent density-functional theory is a formulation of quantummechanics that uses the density as the basic variable. In principle, it provides a computationally attractive approach to non-perturbative processes. We investigate its performance by applying it to the one-dimensional Helium atom in a strong laser field. Specifically, we analyze an approximation of the correlation-potential that is adiabatic in time but exact otherwise. Our results show that this approximation yields excellent results for processes like the Helium double ionization. This finding has important consequences for the development of density-functionals for strong-field processes