This site contains some information about the Density Functional based Tight Binding (DFTB) method which is a fast and efficient quantum mechanical simulation method. It is implemented in the DFTB+ program and in several other program packages. For a (non complete) list of the available codes, see the  implementations subpage.

This site also offers parameters (Slater-Koster files) for the DFTB method. They are free for both, non-commercial and commercial research purposes. See the description of the individual sets for details on the licensing conditions.