Regensburg 2025 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

TT: Fachverband Tiefe Temperaturen

TT 37: Correlated Electrons: Poster

TT 37.7: Poster

Wednesday, March 19, 2025, 15:00–18:00, P4

Bonding in UO₂²⁺ Dumbbell Structures: The Influence of a Non-Orthogonal Atomic Basis Set and the U 5f, 6d, 7s, and 6p Orbitals — •Henrik Hahn, Michelangelo Tagliavini, Kevin Ackermann, Sarah L. Goerlitz, Johann Collard, Ruth Kaiser, and Maurits W. Haverkort — Institute for Theoretical Physics (ITP), Heidelberg University, Philosophenweg 19, 69120, Heidelberg, Germany

Actinide compounds exhibit a wide range of complex properties, making their theoretical description a significant challenge. This complexity arises primarily from the open 5f shell, which introduces strong electronic correlations, as well as the close proximity of multiple subshells with different angular momentum (l) values due to the large principal quantum numbers (n) of actinides. In this study, we investigate the U-O bond in UO₂²⁺, a well-known coordination structure of U²⁺ (5f⁰). Notably, the stronger σ bond derived from the 5f z³ orbital lies higher in energy than the weaker π bonds formed by the 5f xz² and yz² orbitals - an unusual ordering. Through a detailed analysis of the underlying LDA Hamiltonian in a non-orthogonal basis, we provide an explanation for this behavior. Our findings demonstrate that fully understanding the bonding and properties of actinides requires a many-orbital model that transcends the conventional assumption that the low-energy physics is governed solely by the 5f shell. This broader perspective is essential for capturing the intricate electronic structure and bonding characteristics of these materials.

Keywords: Actinides; electronic structure; Density functional theory; chemical bonding; f electron systems