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HL: Fachverband Halbleiterphysik

HL 21: Poster IB (Oxide semiconductors; II-VI and group IV semiconductors; Nanotubes and Buckyballs)

HL 21.28: Poster

Montag, 16. März 2015, 15:00–20:00, Poster B

Lattice dynamics of defect systems: The test case of Si — •Marcel Giar, Andreas Rühl, and Christian Heiliger — I. Physikalisches Institut, Justus-Liebig-University, D-35392 Giessen, Germany

Our research aims at calculating the vibrational properties, in particular Raman spectra, of defect systems. In order to realize sufficiently small defect concentrations very large supercells have to be considered. As a direct first principles approach is computationally too expensive for very large systems (>1000 atoms) we resort to Molecular Dynamics (MD) simulations for calculating lattice dynamical properties of the defect systems. The required effective potentials for carrying out the MD simulations are still based on ab initio data, created in the scope of Force Matching. We test our approach by constructing the respective potential for Si to reproduce phonon spectra obtained from ab initio calculations. The dynamical matrix is obtained within the so called small displacement method, which relies on displacing single atoms and calculating the resulting forces.