Regensburg 2010 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 78: Symposium Density functional theory and beyond for real materials
O 78.6: Hauptvortrag
Donnerstag, 25. März 2010, 17:30–18:00, H1
Calculations of multipoles in magnetic metals and insulators — •Lars Nordström — Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
The concept of spherical tensors or multipoles of an open atomic shell is reviewed and discussed. Some of these multipoles play an important rule in e.g. x-ray circular dichroism measurements, where with the use of the famous sum rules by Carra et al. the spin and orbital magnetic moments can be deduced.
Here we will describe how such multipoles can be calculated in general in both the ground state as well as excited states in terms of density functional methods including a local correlation term, as in e.g. the so-called LDA+U or LDA+DMFT methods. It will be demonstrated how these multipoles can contribute significantly to the exchange and correlation energies of transition metal systems. Especially, we will discuss in some depth materials where these multipoles act as the main order parameter, sometimes referred to as an "hidden order". Results for two cases will be presented the magnetic/superconducting iron-pnictide LaOFeAs and the heavy fermion compound URu2Si2.