Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 22: Theoretical methods

O 22.3: Talk

Monday, March 14, 2011, 17:45–18:00, WIL C107

Stress formulation within the FLAPW method
— •Aaron Klüppelberg, Gustav Bihlmayer, and Stefan Blügel — Peter Grünberg Institut & Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany

Stress is an important quantity in characterizing the states of condensed matter. It can be modified by epitaxial growth relation or application of electric or magnetic fields. This makes the computation of the stress field particularly important for understanding the properties and functionality of ferroic and multiferroic oxides.

The full-potential linearized augmented plane wave (FLAPW) method is an all-electron electronic structure method based on the density functional theory (DFT) that is well suited to describe electronically and structurally complex materials. It is realized in the FLEUR code [1], where orbital-dependent functionals [2] are implemented to describe the exchange-correlation energy of oxides.

We present here a stress-strain formalism for elastic deformations using the frozen augmentation approximation. It takes into account the Pulay corrections to the Hellmann-Feynman stress that appear due to the use of an incomplete basis set (IBS). This procedure allows a simultaneous relaxation of lattice shape and atom positions. Furthermore, this formalism enables the application of pressure and shear making an investigation of phase transitions due to external mechanical impact accessible.
www.flapw.de
M. Betzinger, C. Friedrich, and S. Blügel, PRB 81, 195117 (2010).