Regensburg 2013 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 28: Crystallization, Nucleation and Self Assembly II

CPP 28.5: Vortrag

Mittwoch, 13. März 2013, 16:15–16:30, H40

Free energy and concentration of thermal vacancies in closed-packing solids — •Mostafa Mortazavifar, Mohammad Hossein Yamani, and Martin Oettel — Institut für Angewandte Physik, Eberhard Karls University of Tübingen, Tübingen, Germany

The free energy and the equilibrium concentration of thermally excited vacancies in crystals has been studied since long ago using simulations in classical statistical mechanics or theoretical considerations on the phonon spectrum in the solid with vacancies. Here, we present a simple estimate of the vacancy free energy and concentration in close-packing solids using the leading-order term in an expansion in correlated free particles in a frozen, crystalline matrix [1]. For hard spheres, results are in excellent agreement with available simulation data, and have an intuitive interpretation in terms of available volumes of a free particle in the frozen matrix either next to a vacancy or in a perfect, crystalline surrounding. For solids of atoms interacting with soft potentials, computations can be easily done for broad ranges of temperature and density. We present results for the Lennard-Jones system and compare to available data from simulation and other theory.

[1] Stillinger et al, J. Chem. Phys. 43, 932 (1965).