Dresden 2026 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 51: Correlated Electrons: Method Development II

TT 51.4: Talk

Wednesday, March 11, 2026, 15:45–16:00, HSZ/0101

Embedded Impurity Models with Quantitative Predictive Accuracy: Beyond Mean Field Baths and cRPA — •Kevin Ackermann and Maurits W. Haverkort — Institute for Theoretical Physics, Heidelberg, Germany

Ab-initio embedded impurity approaches, such as DFT+DMFT, are powerful tools for studying correlated materials. However, the interface between the mean-field bath and the many-body impurity presents persistent challenges, particularly in the consistent determination of the screened Coulomb interaction, and the associated double-counting correction.

We address these challenges in the context of transition metal complexes, where an accurate description of the correlated d-electron physics is essential. We present a systematic investigation of electronic g-factors and d-d excitations – sensitive probes of the low-energy electronic structure. Our analysis reveals that achieving quantitative agreement with experimental data requires two components: (1) extending the correlated active space beyond the metal d-orbitals to include relevant ligand states, and (2) incorporating vertex corrections in the calculation of the screened interaction. Only the combination of both yields results consistent with experiment, establishing a clear path toward predictive accuracy in embedded impurity models for coordination complexes.

Keywords: DFT+DMFT; Transition Metal Compounds; Vertex Corrections for cRPA; Molecular Magnets; Correlated Materials