Density-Functional based Tight-Binding (DFTB) allows to perform calculations of large systems over long timescales even on a desktop computer. Relatively accurate results are obtained at a fraction of the cost of DFT by using pre-calculated parameters, a minimal basis and only nearest-neighbor interactions. Long-range interactions are described with empirical dispersion corrections and third-order corrections accurately handle charged systems.
The DFTB module can treat molecular as well as periodic systems (1D for nanotubes, 2D for surfaces, 3D for bulk), and as such can be used as a fast pre-optimizer for full molecular and periodic DFT calculations with ADF and BAND. From AMS2019 onwards, the DFTB license also includes the semi-empirical MOPAC library, which implements another tight binding method similar to DFTB.