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MM: Fachverband Metall- und Materialphysik

MM 16: Phase transitions II

MM 16.1: Vortrag

Dienstag, 27. März 2007, 11:45–12:00, H4

Metadynamics Simulations of Phase Transitions in Solids — •Jörg Behler¹, Davide Donadio¹, Roman Martoňák², and Michele Parrinello¹ — ¹ETH Zurich, Department of Chemistry and Applied Biosciences, USI Campus, Lugano, Switzerland — ²Comenius University, Department of Experimental Physics, Bratislava, Slovakia

The theoretical prediction of crystal structures for a given pressure and temperature based only on the chemical composition is still a challenging task. We present a combination of the metadynamics approach, which uses the edges of the simulation cell as collective variables to drive the system away from the local minimum towards a new crystal structure, and an efficient generalized neural network potential representation, which provides the energy and forces as a function of all atomic positions in a system of arbitrary size. This potential is several orders of magnitude faster than the underlying density-functional theory (DFT) calculations while the accuracy of DFT is essentially maintained. The capability of the method is demonstrated for a silicon model system and the results obtained are in excellent agreement with experiment.