g-xTB: DFT accuracy at tight-binding speed

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• Professor Stefan Grimme, University of Bonn
• Wednesday 05 March 2025, 14:30-15:30
• Unilever Lecture Theatre, Yusuf Hamied Department of Chemistry.

If you have a question about this talk, please contact Lisa Masters.

Recently, we optimized small (vDZP), deeply contracted AO basis sets in molecular DFT calculations using standard ECPs for all elements up to radon¹. This strategy is further- more applied to a minimal set of AOs which — as a totally new ingredient — is made adaptive, i.e., radially different for symmetry distinct atoms in a molecule. The ”breathing” of the AOs in the molecular environment is parameterized efficiently by on-the-fly computed effective atomic charges (obtained by a new EEQ charge model) and coordination numbers. This so-called q-vSZP set² provides in typical DFT applications results of about or better than DZ quality. It forms the basis of our third-generation tight-binding model g-xTB (g=general). This includes non-local Fock-exchange as well as other new, many-center Hamiltonian terms (e.g., atomic correction potentials, ACP ). It aims at general purpose applicability in chemistry and more closely approaches DFT accuracy (actually ωB97M-V/aTZ³) than previous semi-empirical methods at only slightly increased computational cost (factor of 1.5 compared to GFN2 -xTB). It will be consistently available for all elements Z=1-103 with f-electrons included for lanathanides/actinides. The talk describes key improvements of the underlying TB theory as well as extensive benchmarking on a wide range of standard thermochemistry sets. [1] M. Müller, A. Hansen, S. Grimme, J. Chem. Phys. 158 (2023), 014103 [2] M. Müller, A. Hansen, S. Grimme, J. Chem. Phys. 159 (2023), 164108. Revision: JPC A , doi:10.1021/acs.jpca.4c06989 [3] N. Mardirossian and M. Head-Gordon, J. Chem. Phys. 144 (2016), 214110

This talk is part of the Theory - Chemistry Research Interest Group series.

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