  A long standing problem in time dependent density functional theory (TD-DFT)
has been the absence of a functional able to capture excitonic physics under
laser pump conditions. Here we introduce a Kohn-Sham-Proca scheme that we
demonstrate reproduces both linear response excitonic effects in the absorption
in excellent agreement with experiment for a wide range of materials, but also
captures excitonic physics in the highly non-linear regime of ultrafast laser
pumping, in particular laser fluence dependent "bleaching" (i.e. reduction) of
the excitonic weight and the appearance of excitonic side bands. The approach
is a procedural functional -- the Kohn-Sham and Proca equations are
simultaneously time propagated -- allowing the straight-forward inclusion of,
for example, lattice and spin degrees of freedom into excitonic physics.
