Transport properties and a current-functional theory in the linear-response regime.

The possibility of formulating a time-dependent current-functional theory which describes the linear responses of systems of inhomogeneous, interacting electron gas to an arbitrary form of time-dependent electromagnetic field is studied. A Kohn-Sham-type theory for the dynamical electronic conductivity tensor is derived and a local-density type of approximation for the resulting exchange-correlation electric field is constructed.