Berlin 2015 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 30: Methods in Computational Materials Modelling III: Thermodynamics

MM 30.3: Vortrag

Mittwoch, 18. März 2015, 10:45–11:00, H 0106

Sampling of temperature-dependent interactions within the cluster-expansion framework — •Sascha B. Maisel, Albert Glensk, Dominique Korbmacher, Tilmann Hickel, Blazej Grabowksi, and Jörg Neugebauer — Max-Planck Institute for Iron Research, Max-Planck Strasse 1, 40239 Duesseldorf, Germany

Temperature-dependent effective interactions are an enormous improvement over classical n-body Hamiltonians for a variety of reasons. Advantages include a better description of an alloy’s remnant solubility in the dilute limit and more accurate predictions at high temperatures, where phonons are non-neglibible. We compare two different methods for sampling such temperature-dependent interaction strengths for the cluster-expansion method. The first method extends upon earlier work by Reith et al., by including quasi-harmonic and electronic excitations contributing to the Gibbs free energy based on density functional theory phonon calculations. The second method samples temperature-dependent effective interactions directly from finite temperature ab-initio molecular dynamics simulations. Variations of this sampling procedure can deal with large interatomic relaxations far better than conventional sampling. We discuss the advantages, shortcomings and computational cost of both methods based on preliminary results for the Ni-Ti and Al-Sc systems.