Density functional tight binding: application to organic and biological molecules

In this work, we review recent extensions of the density functional tight binding (DFTB) methodology and its application to organic and biological molecules. DFTB denotes a class of computational models derived from density functional theory (DFT) using a Taylor expansion around a reference density. The first- and second-order models, DFTB1 and DFTB2, have been reviewed recently (WIREs Comput Mol Sci 2012, 2:456-465). Here, we discuss the extension to third order, DFTB3, which in combination with a modification of the Coulomb interactions in the second-order formalism and a new parametrization scheme leads to a significant improvement of the overall performance. The performance of DFTB2 and DFTB3 for organic and biological molecules are discussed in detail, as well as problems and limitations of the underlying approximations. (C) 2013 John Wiley & Sons, Ltd. WIREs Comput Mol Sci 2014, 4:49-61. doi: 10.1002/wcms.1156 The authors have declared no conflicts of interest in relation to this article. For further resources related to this article, please visit the WIREs website.