Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 20: Theoretical methods I

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. Mostofi31Cavendish 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 [1]. Our implementation within the ONETEP code [2] 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 [3], which may be self-consistently optimized [4].

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.

[1] O’Regan, Hine, Payne and Mostofi, submit. (2011), arXiv:1111.5943.

[2] Hine et. al. Comp. Phys. Commun., 180, 1041 (2009).

[3] O’Regan, Payne and Mostofi, PRB 83, 245124 (2011).

[4] O’Regan, Hine, Payne and Mostofi, PRB 82, 081102(R) (2010).

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