Dresden 2017 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 5: Correlated Electrons: (General) Theory 1

TT 5.9: Vortrag

Montag, 20. März 2017, 11:45–12:00, HSZ 304

Modeling correlated systems: from atoms to materials — •Qian Zhang and Erik Koch — Institute for Advanced Simulation, Forschungszentrum Jülich, 52428 Jülich, Germany

The study of strongly correlated materials requires careful treatment of electron-electron interactions. Our starting point is density functional calculations for individual atoms and ions to obtain realistic basis functions. In particular, we focus on the open-shell orbitals, which have the strongest correlation effects. While atomic orbitals are mutually orthogonal within a single atom, they are in general not orthogonal for atoms on different lattice sites. We will discuss multi-center integral techniques for evaluating orbital overlaps, which are essential for performing orbital orthogonalization. This allows us to study atomic orbitals in various crystal structures. To orthogonalize the basis orbitals, we apply the Löwdin symmetric orthogonalization scheme which leads to the minimum orbital modification. For the resulting orbitals, we study the deformation due to orthogonalization, and investigate how the Coulomb matrix elements are changed compared with the atomic ones.