[GS_C_QMT] Resonant X-ray Scattering and Charge Disproportionation: A Dynamical Mean-Field Theory Perspective
ABSTRACT
Starting from the chemical principle of charge neutrality, one can infer the oxidation states of elements in compounds—especially those involving transition metals in insulating states. However, a more accurate approach for estimating oxidation states is the bond valence sum model, which relies on experimental crystal structure data. This method can sometimes yield fractional oxidation states, which are further examined using experimental techniques such as resonant X-ray scattering (RXS), often supported by empirical arguments.
Despite its usefulness, interpreting RXS data through numerical methods often reveals only minimal charge disproportionation, seemingly at odds with oxidation states estimated chemically. In this presentation, I will first provide a concise overview of the RXS technique. Then, using embedded dynamical mean field theory (eDMFT), I will present an alternative perspective on chemically derived oxidation states, focusing on compounds containing Fe and Mn ions in high oxidation states.
This alternative viewpoint suggests that what is often interpreted as "charge disproportionation" may, in fact, reflect the emergence of novel states of matter characterized by site- or orbital-selective electronic behavior.
