Beyond dynamic density functional theory: the role of inertia

We discuss the recent attempts to generalize dynamical density functional (DDF) theory to situations where the momentum and energy transport, not necessarily associated with mass diffusion, play a role. We consider an assembly of particles described by inertial dynamics and subjected to the influence of a heat-bath. By means of a time multiple timescale analysis we derive the evolution equation for the noise-averaged density field. Remarkably, for large values of the friction parameter and/or the mass of the particles we obtain the same governing equation of DDF, and in addition we are able to compute higher-order corrections.