Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 26: Focussed session: Theory and computation of electronic structure: new frontiers II (jointly with HL, DS)
O 26.6: Vortrag
Dienstag, 15. März 2011, 12:45–13:00, TRE Phy
Issues with J-dependence in the LSDA+U method for non-collinear magnets — •Eric Bousquet1,2 and Nicola Spaldin1 — 1Department of Materials, ETH Zurich, Switzerland — 2Physique Théorique des Matériaux, Université de Liège, B-4000 Sart Tilman, Belgium
We re-examine the commonly used density functional theory plus Hubbard U DFT+U method for the case of non-collinear magnets. While many studies neglect to explicitly include the exchange correction parameter J, or consider its exact value to be unimportant, here we show that in the case of non-collinear magnetism calculations the J parameter can strongly affect the magnetic ground state. We illustrate the drastic J-dependence of magnetic canting, magnetoelectric response and magnetocrystalline anisotropy by calculating trends in the magnetic lithium orthophosphate family LiMPO4 (M = Fe and Ni) and difluorite family MF2 (M = Mn, Fe, Co and Ni). These results can be readily understood by expanding the usual DFT+U equations within the spinor scheme. On the flip side, it is clear that non-collinear magnetic systems provide a challenging case for testing the correctness of new exchange correlation functionals within the density functional formalism.