Berlin 2012 – wissenschaftliches Programm
O 20.4: Vortrag
Montag, 26. März 2012, 18:30–18:45, A 060
A linear-scaling DFT+U study of Friedel oscillations and localization in very dilute Gallium Manganese Arsenide — •David D. O’Regan1,2, Nicholas D. M. Hine1,3, Mike C. Payne1, and Arash A. Mostofi3 — 1Cavendish Laboratory, University of Cambridge. — 2Theory and Simulation of Materials, École Polytechnique Fédérale de Lausanne. — 3The Thomas Young Centre and the Department of Materials, Imperial College London.
We tackle the long-standing difficulties of large system size and strong electronic correlation simultaneously in this work, demonstrating a linear-scaling DFT+U method . Our implementation within the ONETEP code  allows for full local orbital optimization and thus systematic variational convergence, and we demonstrate scaling up to 7,000 atoms. Our method furthermore allows for nonorthogonal projectors , which may be self-consistently optimized .
The ferromagnetic interaction between distant localized magnetic moments in the prototypical dilute magnetic semiconductor (Ga,Mn)As is mediated by defect-induced holes, whose long-ranged character is critical. We present DFT+U calculations of 1,728 atom super-cells of (Ga,Mn)As, accessing the very dilute (0.1%) limit. We analyze the localization and symmetry of the hole density, and characterize its long-range Friedel oscillations.
 O’Regan, Hine, Payne and Mostofi, submit. (2011), arXiv:1111.5943.
 Hine et. al. Comp. Phys. Commun., 180, 1041 (2009).
 O’Regan, Payne and Mostofi, PRB 83, 245124 (2011).
 O’Regan, Hine, Payne and Mostofi, PRB 82, 081102(R) (2010).