8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Wed 711:10-14:00P5.9Stability of ordered soft disks through linear theory ofelasticityLabrini Athanasopoulou 1 and Primoz Ziherl 11 Department of Theoretical Physics, Jozef Stefan Institute, Ljubljana, 39 Jamova cesta,1000, Ljubljana, SloveniaPrevious works have shown that nano-colloidal systems at large densities can be self-assembledinto non-close-packed lattices, i. e. bcc, A15, lattices and quasicrystals. The stability of suchlattices is of great interest as these are more deformable than the common ones with a single typeof lattice site, like fcc, hcp and bcc, and exhibit fascinating behaviour. In order to approach thestability of the aforementioned open structures we start studying the stability of four differentordered structures of soft disks: hexagonal, square, honeycomb, columnar, using basic notionsfrom the theory of elasticity. Under this framework the coordination number of disks in contactdepends crucially on the Poisson ratio which controls the degree of dilation after the deformationbecause of elastic interactions between nearest neighbours. Prompted by up-to-date literature,where the Hertzian model is extensively used to describe those kinds of interactions, we examinethe density range where the Hertzian model is valid. Thereafter, we explore the behaviour of thedisks at large densities, focusing on the limitations of the linear theory of elasticity for solids. Ourresults are outlined in the phase diagram for the lattices under investigation.[1] V. S. K. Balagurusamy, G. Ungar, V. Percec and G. Johansson, J. am. Chem. Soc.119, 1539 (1997).[2] X. Zeng, G. Ungar, V. Percec, A. E. Dulcey and J. A. Hobbs, Nature 428, 157 (2004).[3] S. Prestipino, F. Saija and G. Malescio, Soft Matter 5, 2795 (2009).[4] J. C. Pamies, A. Cacciouto and D. Frenkel, J. Chem. Phys. 131, 044514 (2009)9