  We present a new time-dependent Density Functional approach to study the
relaxational dynamics of an assembly of interacting particles subject to
thermal noise. Starting from the Langevin stochastic equations of motion for
the velocities of the particles we are able by means of an approximated closure
to derive a self-consistent deterministic equation for the temporal evolution
of the average particle density.
  The closure is equivalent to assuming that the equal-time two-point
correlation function out of equilibrium has the same properties as its
equilibrium version.
  The changes in time of the density depend on the functional derivatives of
the grand canonical free energy functional $F[\rho]$ of the system. In
particular the static solutions of the equation for the density correspond to
the exact equilibrium profiles provided one is able to determine the exact form
of $F[\rho]$. In order to assess the validity of our approach we performed a
comparison between the Langevin dynamics and the dynamic density functional
method for a one-dimensional hard-rod system in three relevant cases and found
remarkable agreement, with some interesting exceptions, which are discussed and
explained. In addition, we consider the case where one is forced to use an
approximate form of $F[\rho]$.
  Finally we compare the present method with the stochastic equation for the
density proposed by other authors [Kawasaki,Kirkpatrick etc.] and discuss the
role of the thermal fluctuations.
