Seminari: "New DFT approaches beyond the zero-sum game and more"






Institut de Química Teòrica i Computacional



Conferenciant: Martin Kaupp (Technische Universität Berlin).

Resum: I will give an overview over some of the recent, exciting progress we have made in the field of local hybrid functionals (LHs) and beyond, which I think opens a new era in the field. Position-dependent exact-exchange admixture of LHs like LH20t allows a flexible treatment of properties depending on different spatial regions, e.g. in the core, valence, far away from the nuclei, or in different parts of a larger composite system. This has been explored, e.g., for NMR and EPR parameters, including the setup of new benchmark sets of unprecedented scope for NMR shifts for main-group and transition-metal nuclei. We recently extended the efficient implementation of LHs in Turbomole to range-separated LHs and reported the wLH22t long-range corrected RSLH, which rivals the optimally-tuned RSH approach for quasiparticle energies in molecular electronics, without the need for system-dependent tuning. The most exciting progress is the introduction of strong-correlation factors into LHs and RSLHs that allows us to escape the usual zero-sum game between reducing fractional charge errors (self-interaction errors) and fractional spin errors (static correlation errors). This provides powerful new DFT approaches and opens a wide range of possible applications, including in particular for transition-metal systems. Many of the new methods have just become available with Turbomole 7.8. Time permitting I will also talk about spin-state splittings of 3d complexes, where the new CASPT2+dMRCI composite benchmark method offers new insights, and I may address the recent solution to the previously controversial puzzle of the mixed-valent Rydberg state of dimethylpiperazine.

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