Speaker: Yannick Franzke, Karlsruher Institut für Technologie

The development of density functional approximations strongly focuses on the electronic structure. However, DFT is not only applicable to electrons but also to other fermions within the framework of multicomponent DFT. Ideally, a general density functional approximation applicable to electrons, protons, and other Fermions with similar accuracy should be constructed. This requires a tailored correlation term, which should be derived in a non-empirical way to ensure transferability. Utilizing the class of local hybrids (LHs), we construct exchange-correlation functionals from first principles and show that theoretical constraint satisfaction can be achieved with full exact exchange without sacrificing accuracy [1]. Here, LHs are especially advantageous for strongly localized fermions such as protons, as they allow to smoothly switch from 0% to 100% exact exchange and thus mitigate the self-interaction error.

The new functional shows excellent performance for thermochemical properties, excitation energies, NMR properties, and Mossbauer isomer shifts. The transferability to other Fermions is illustrated for electron-proton correlation energies and compared to results from the multicomponent random phase approximation [2].

Our implementation in TURBOMOLE uses an efficient seminumerical scheme [3] and is available in a relativistic two-component formalism to include spin-orbit interaction [4,5]. Therefore, it is applicable to a wide range of real-world systems, as demonstrated for the NMR shifts of organophosphorous molecules [6] and EPR properties of Bi or Tl compounds.

[1] C. Holzer, Y. J. Franzke, J. Chem. Theory Comput. 21, 202 (2025).
[2] C. Holzer, Y. J. Franzke, ChemPhysChem 25, e202400120 (2024).
[3] C. Holzer, J. Chem. Phys. 153, 184115 (2020).
[4] C. Holzer, Y. J. Franzke, A. Pausch, J. Chem. Phys. 157, 204102 (2022).
[5] Y. J. Franzke, A. Pausch, C. Holzer, J. Chem. Phys. 162, 04104 (2025).
[6] L. A. Steffen, L. S. Szych, Y. J. Franzke, R. O. Kopp, M. J. Ernst, M. Weber, C. Mueller, submitted.