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This 25-minute Lennard-Jones Centre discussion group seminar features Prof. Lucian Pascut from Stefan Cel Mare University (USV) Suceava in Romania exploring charge disproportionation through dynamical mean field theory. Discover how traditional methods of determining oxidation states in transition metal compounds can be challenged by more sophisticated approaches. Learn about the bond valence sum model that utilizes experimental crystal structures, often yielding fractional oxidation states that are verified through resonant X-ray scattering (RXS). Understand the contradictions between estimated oxidation states and numerical interpretations of RXS experiments that indicate minimal charge disproportionation, including examples in metallic systems like 2H-AgNiO2. Gain insights into the fundamentals of the RXS method and explore an alternative perspective on chemically estimated oxidation states using dynamical mean field theory (DMFT) with compounds such as NdNiO3, CaFeO3, LaMnO3, and BiMnO3 as examples. Examine how "charge disproportionation" may actually indicate the emergence of unique states of matter with site or orbital selectivity, where fascinating phenomena occur including non-equivalent crystallographic sites showing both Mott and band-like insulator characteristics, or the coexistence of metallic and insulating orbitals within the same crystallographic site. This seminar was recorded on November 13, 2023.
