Regensburg 2010 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 55: Topical Session Growth Kinetics V

MM 55.3: Vortrag

Donnerstag, 25. März 2010, 14:30–14:45, H4

Minimum Energy Path for Nucleation with Phase Field Crystal — •Axel Voigt and Rainer Backofen — TU Dresden

Phase Field Crystal (PFC) is a well established model to study solidification in metals and colloids on an atomistic scale [1,2]. It can be connected to time dependent classical density functional theory. The time evolution of the density of particles is governed by a (at least) 6-th order partial differential equation. Thus, it is straight forward to calculate the time evolution of states, which is a minimization of total energy in the system. But, in order to study nucleation, the transition path between two (meta) stable states has to be explored. The nucleation barrier is then defined by the most probable transition path. This is equivalent to the minimum energy path (MEP). The MEP is the path in configuration space, where the driving force or dynamics of the system is parallel to the transition path [3]. Thus, the MEP allows us to identify saddle points which has to be overcome by nucleation as well as nucleation barriers. Recently a simplified string method was proposed in order to calculate MEP in high dimensional configuration spaces [3]. We will show the application of the simplified string method to nucleation in phase field crystal. Nucleation barriers as well as morphology of minimal stable nuclei will be discussed. Furthermore the influence of walls to nucleation will be shown.

[1] S. van Teeffelen, R. Backofen, A. Voigt and H. Loewen, Phys. Rev. E 79 051404 (2009) [2] R. Backofen, A. Raetz and A. Voigt, Phil. Mag. Let. 87 (11),(2007) [3] W. E, W. Ren and E. Vanden-Eijnden, J Chem. Phys. 126, 164103 (2007)