  Materials with strong electronic Coulomb correlations play an increasing role
in modern materials applications. "Thermochromic" systems, which exhibit
thermally induced changes in their optical response, provide a particularly
interesting case. The optical switching associated with the metal-insulator
transition of vanadium dioxide, for example, has been proposed for use in
numerous applications, ranging from anti-laser shields to "intelligent"
windows, which selectively filter radiative heat in hot weather conditions. Are
present-day electronic structure techniques able to describe, or -- eventually
even predict -- such a kind of behavior ? How far are we from materials design
using correlated oxides ? These are the central questions we try to address in
this article. We review recent attempts of calculating optical properties of
correlated materials within dynamical mean field theory, and summarize results
for vanadium dioxide obtained within a novel scheme aiming at particularly
simple and efficient calculations of optical transition matrix elements within
localized basis sets. Finally, by optimizing the geometry of "intelligent
windows", we argue that this kind of technique can in principle be used to
provide guidance for experiments, thus giving a rather optimistic answer to the
above questions.
