Effective potentials for quasicrystals from ab-initio data

Abstract

Classical effective potentials are indispensable for any large-scale atomistic simulations, and the relevance of simulation results crucially depends on the quality of the potentials used. For complex alloys such as quasicrystals, however, realistic effective potentials are almost non-existent. We report here our efforts to develop effective potentials especially for quasicrystalline alloy systems. We use the so-called force-matching method, in which the potential parameters are adapted so as to reproduce the forces and energies optimally in a set of suitably chosen reference configurations. These reference data are calculated with ab-initio methods. As a first application, embedded-atom method potentials for decagonal Al–Ni–Co, icosahedral Ca–Cd, and both icosahedral and decagonal Mg–Zn quasicrystals have been constructed. The influence of the potential range and degree of specialization on the accuracy and other properties is discussed and compared.

Acknowledgements

This work was funded by the Deutsche Forschungsgemeinschaft through Sonderforschungsbereich 382. Special thanks are due to Marek Mihalkovič for supplying approximants and feedback in the Ca–Cd and Mg–Zn systems, and to Hans-Rainer Trebin for supervising the thesis work of the first author.