Pymatgen (Python Materials Genomics) is a robust, open-source Python library
for materials analysis. These are some of the main features:
* Highly flexible classes for the representation of Element, Site, Molecule,
  Structure objects.
* Extensive input/output support, including support for VASP
  (http://cms.mpi.univie.ac.at/vasp/), ABINIT (http://www.abinit.org/), CIF,
  Gaussian, XYZ, and many other file formats.
* Powerful analysis tools, including generation of phase diagrams, Pourbaix
  diagrams, diffusion analyses, reactions, etc.
* Electronic structure analyses, such as density of states and band structure.
* Integration with the Materials Project REST API, Crystallography Open
  Database.

WWW: http://pymatgen.org/