Libxc is library of exchange-correlation functionals for density-functional
theory.  The aim is to provide a portable, well tested and reliable set of
exchange and correlation functionals that can be used by all the ETSF codes
and also other codes.

In libxc you can find different types of functionals: LDA, GGA, hybrids,
and mGGA (experimental).

WWW: http://www.tddft.org/programs/octopus/wiki/index.php/Libxc