Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 19: Computational Materials Modelling IV - Finite Temperature
MM 19.2: Vortrag
Dienstag, 27. März 2012, 10:30–10:45, TC 006
Fully ab initio determination of anharmonic contributions by efficient sampling strategies — •Albert Glensk1, Blazej Grabowski2, Tilmann Hickel1, and Joerg Neugebauer1 — 1Max-Planck Institut für Eisenforschung — 2Lawrence Livermore National Lab
Using ab initio approaches, temperature dependent thermodynamic free energies are nowadays typically calculated within the quasiharmonic approximation. Numerically highly accurate ab initio calculations for Al including anharmonic contributions on the other hand showed a significant change in the heat capacity and a dramatic effect on the entropy of vacancy formation in Al compared to quasiharmonic results [1]. By developing and implementing highly efficient sampling methods, we are now able to routinely determine anharmonic contributions for metals. Using these methods we were able to systematically improve the ab initio based thermodynamic description of Al-Mg-Si-Cu alloys. Particularly, the influence of anharmonicities on the unary subsystems of these alloys, consequences for the phase diagrams and deviations from quasiharmonic results will be discussed.
[1] B. Grabowski et al, PRB 79, 134106 (2009)