Density-Functional based Tight-Binding (DFTB) enables calculations on large systems for long timescales even on a desktop computer. Relatively accurate results are obtained at a fraction of the cost of DFT by reading in pre-calculated parameters (Slater-Koster files), using a minimal basis and only including nearest-neighbor interactions. Long-range interactions are described with empirical dispersion corrections and third-order corrections accurately handle charged systems.
Our 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. In collaboration with Thomas Heine (Leipzig), we strive to continuously improve the ADF/DFTB module, in particular to include more properties and DFTB parameters for the whole periodic table.