Quantum Atomistic Solid-State Theory: CeRh_{2}Si_{2}, K_{2}CoF_{4}, LaCoO_{3}, Sr_2VO_{4}, Ba_{2}IrO_{4} and Sr_{2}RuO_{4}

Abstract

The propagated crystal-field-based quantum atomistic solid-state theory starts the theoretical description of a solid containing open d/f shell atoms from the analysis of charge states and low-energy crystal-field discrete electronic structure of 3d/4f/5f/4d/5d ions. The crystal-field-based description of CeRh₂Si₂ Kondo-lattice antiferromagnetic intermetallics proves that crystal-field states exist in the compounds' "conducting current". In oxides, the realized cation valency is basically equal to the formal valency from the ionic model. The realized valency can be experimentally verified by having its own finger print in the excitation spectrum. Even weak spin–orbit interactions in 3d ions are responsible for the violation of the Curie–Weiss law at low temperatures, and for the realization of the nonmagnetic state, especially for non-Kramers ions, as it is in the case of Sr₂RuO₄. The quantum atomistic solid-state theory methodology "From atomic physics to solid-state physics" is very fruitful and offers a consistent picture of transition-metal compounds.