Regensburg 2007 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 30: Poster II
DY 30.6: Poster
Donnerstag, 29. März 2007, 16:00–18:00, Poster D
Colloidal Crystals in 2D: elasticity, structures and phase transitions — •Kerstin Franzrahe and Peter Nielaba — Department of Physics, University of Konstanz, 78457 Konstanz, Germany
Thin films on a substrate can be modelled by two dimensional colloidal systems. The influence of the substrate can be varied by adjusting e.g. the amplitude of an additional external laser field. We investigate the elastic and structural properties of such systems via Monte-Carlo simulations. Our model system consists of particles interacting via a hard-disk potential. For the field free case the influence of quenched impurities on the elastic properties of a mono-disperse system [1] is examined, while in the study of bi-disperse systems our focus is on the stability of crystalline structures for various size and mixing ratios. Modelling the effect of the substrate on the two dimensional crystal, we study the influence of a commensurable, spatially periodic, external laser field on a bi-disperse S1(AB) crystal. We observe laser induced freezing (LIF).
The fluctuations of the microscopic strains in a solid contain information on the elastic properties of the system. Generalising the approach by S. Sengupta et.al.[2], we analyse the strain correlation functions of a harmonic two dimensional system. The analysis shows that these correlations are highly anisotropic in the solid.
[1] K. Franzrahe et. al., Comp. Phys. Commun. 169,pp 197-202 (2005)
[2] S. Sengupta, P. Nielaba, M. Rao and K. Binder,Phys. Rev. E 61, pp. 1072 (2000)