Time-dependent extension of the Hohenberg-Kohn-Levy energy-density functional

An energy-minimization principle based on the hydrodynamic formulation of quantum mechanics is used to develop a time-dependent energy-density functional. The external potential considered has a periodic dependence on time and the validity of the functional is restricted to those frequencies which are not so large as to cause a transition to an excited state. The present time-dependent energy-density functional reduces to the time-independent Hohenberg-Kohn-Levy functional in the static limit.