Choi

Cheol Ho Choi (Kyungpook National University)
Mixed-Reference Spin-Flip TDDFT: A Versatile Quantum-Chemical Engine for Challenging Electronic States
31 July 2025 (Tue) 15:00-16:00 Science and Technology Research Building #4 807 Seminar Room
Abstract
Mixed-Reference Spin-Flip Time-Dependent Density-Functional Theory (MRSF-TDDFT) resolves two long-standing limitations of conventional linear-response methods: (i) the need to describe electronic configurations that lie beyond a single-reference picture and (ii) the absence of nondynamic correlation within Kohn–Sham DFT. By embedding the spin-flip formalism in a “hypothetical single-reference” framework, MRSF-TDDFT naturally incorporates multi-reference character while retaining the computational efficiency of TDDFT. This unified treatment delivers balanced accuracy for demanding phenomena across both ground and excited states—diradicals, bond dissociation, conical intersections, doubly excited states, and core-level spectroscopy—hallmarks that traditionally require far more expensive wave-function approaches. The presentation will (1) unpack the conceptual underpinnings of the mixed reference and its implication for linear-response theory, and (2) showcase benchmark results that highlight the method’s reliability in the aforementioned regimes. Together, these advances position MRSF-TDDFT as a practical, general-purpose tool for decoding complex molecular and material electronic structures.