Rabi oscillations in time-dependent density functional theory

The use of functionals from static density-functional theory in an adiabatic way in a time-dependent frame-work is known to cause various problems due to the resulting exchange-correlation kernel being frequencyindependent. Using a simple one-dimensional two-electron system, which can be solved exactly, we investigatethe behavior of the adiabatic local density approximation and the adiabatic exact-exchange approximationfor the description of Rabi oscillations. We find that the quality of the results depends on the ground andexcited states that are involved in the Rabi oscillations and the number of electrons that participate in theexcitation. From these results we conclude that apart from the frequency dependence one also needs to in-clude correlation properly in order to describe resonant Rabi oscillations in the framework of time-dependentdensity-functional theory.References[1] J.I. Fuks, N. Helbig, I.V. Tokatly, A. Rubio, Phys. Rev. B 84, 75107 (2011