Implementation and benchmark of a long-range corrected functional in the\n density functional based tight-binding method

Bridging the gap between first principles methods and empirical schemes, the\ndensity functional based tight-binding method (DFTB) has become a versatile\ntool in predictive atomistic simulations over the past years. One of the major\nrestrictions of this method is the limitation to local or gradient corrected\nexchange-correlation functionals. This excludes the important class of hybrid\nor long-range corrected functionals, which are advantageous in thermochemistry,\nas well as in the computation of vibrational, photoelectron and optical\nspectra. The present work provides a detailed account of the implementation of\nDFTB for a long-range corrected functional in generalized Kohn-Sham theory. We\napply the method to a set of organic molecules and compare ionization\npotentials and electron affinities with the original DFTB method and higher\nlevel theory. The new scheme cures the significant overpolarization in electric\nfields found for local DFTB, which parallels the functional dependence in first\nprinciples density functional theory (DFT). At the same time the computational\nsavings with respect to full DFT calculations are not compromised as evidenced\nby numerical benchmark data.\n