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Parametrization and Benchmark of DFTB3 for Organic Molecules

2012; American Chemical Society; Volume: 9; Issue: 1 Linguagem: Inglês

10.1021/ct300849w

1549-9626

Michael Gaus, Albrecht Goez, Marcus Elstner,

Spectroscopy and Quantum Chemical Studies

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.