Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 8: Computational Materials Modelling II - Methods

MM 8.2: Vortrag

Montag, 26. März 2012, 12:00–12:15, TC 006

An evolution strategy for crystal structure prediction — •Silvia Bahmann, Thomas Gruber, and Jens Kortus — TU Bergakademie Freiberg, Institute for Theoretical Physics, Leipziger Str. 23, 09596 Freiberg, Germany

The crystal structure determines many physical properties. For materials design of new systems with a given chemical composition one therefore needs the ability to predict possible crystal structures. The challenge in this prediction lies in the facts that it is a global search in a search space that grows exponentially with the number of atoms per unit cell and the unknown energy landscape containing several minima.

Our evolutionary strategy uses the main features of natural evolution - recombination, mutation, selection and the survival of the fittest - to global search. The crystal structures represent the individuals in this picture whereas their fitness value is determined by calculating the free energy of the individual using electronic structure programs. The individual having the minimal free energy in the whole search space is considered to be the most stable structure. The combination of the effective local optimisation already implemented in electronic structure programs with stochastic elements of the evolution strategy ensures an efficient search.

We present the developed evolution strategy designed for general 3D crystal structure prediction that also features the search of 2-dimensional structures. As an application we focus here on the search for 3D structures of lithium-silicides that are promising for new electrode materials for lithium ion batteries.