title: Parametrization and Benchmark of DFTB3 for Organic Molecules.
abstract: DFTB3 is a recent extension of the self-consistent-charge density-functional tight-binding method (SCC-DFTB) and derived from a third order expansion of the density functional theory (DFT) total energy around a given reference density. Being applied in combination with the parametrization of its predecessor (MIO), DFTB3 improves for hydrogen binding energies, proton affinities, and hydrogen transfer barriers. In the present study, parameters especially designed for DFTB3 are presented, and its performance is evaluated for small organic molecules focusing on thermochemistry, geometries, and vibrational frequencies from our own and several databases from literature. The new parameters remove significant overbinding errors, reduce errors for geometries of noncovalent interactions, and improve the overall performance.
authors.affiliation: Institute of Physical Chemistry, Karlsruhe Institute of Technology, Kaiserstr. 12, 76131 Karlsruhe, Germany.|Department of Chemistry and Theoretical Chemistry Institute, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Gaus
authors.affiliation: Institute for Physical and Theoretical Chemistry, Braunschweig Institute of Technology, Hans-Sommer-Str. 10, 38106 Braunschweig, Germany.
authors.forename: Albrecht
authors.initials: A
authors.lastname: Goez
authors.affiliation: Institute of Physical Chemistry, Karlsruhe Institute of Technology, Kaiserstr. 12, 76131 Karlsruhe, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Elstner