title: DFTB Parameters for the Periodic Table, Part 2: Energies and Energy Gradients from Hydrogen to Calcium.
abstract: In the first part of this series, we presented a parametrization strategy to obtain high-quality electronic band structures on the basis of density-functional-based tight-binding (DFTB) calculations and published a parameter set called QUASINANO2013.1. Here, we extend our parametrization effort to include the remaining terms that are needed to compute the total energy and its gradient, commonly referred to as repulsive potential. Instead of parametrizing these terms as a two-body potential, we calculate them explicitly from the DFTB analogues of the Kohn-Sham total energy expression. This strategy requires only two further numerical parameters per element. Thus, the atomic configuration and four real numbers per element are sufficient to define the DFTB model at this level of parametrization. The QUASINANO2015 parameter set allows the calculation of energy, structure, and electronic structure of all systems composed of elements ranging from H to Ca. Extensive benchmarks show that the overall accuracy of QUASINANO2015 is comparable to that of well-established methods, including PM7 and hand-tuned DFTB parameter sets, while coverage of a much larger range of chemical systems is available.
authors.affiliation: Department of Physics & Earth Sciences, Jacobs University Bremen , Campus Ring 1, 28759 Bremen, Germany.
authors.forename: Augusto F
authors.initials: AF
authors.lastname: Oliveira
authors.affiliation: Scientific Computing & Modelling NV, Theoretical Chemistry, Vrije Universiteit , De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
authors.forename: Pier
authors.initials: P
authors.lastname: Philipsen
authors.affiliation: Department of Physics & Earth Sciences, Jacobs University Bremen , Campus Ring 1, 28759 Bremen, Germany.|Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig , Linnéstr. 2, 04103 Leipzig, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Heine