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

Wed 711:10-14:00P5.187Freezing behavior of parallel hard spherocubesUrs Zimmermann, 1 Matthieu Marechal, 2 and Hartmut Löwen 21 Heinrich-Heine-Universität Düsseldorf, Institut für Theoretische Physik II, Universitätsstra1 D-40225, Düsseldorf, Germany2 Heinrich-Heine-Universität Düsseldorf, Düsseldorf, GermanyThe monocomponent fluid of parallel hard cubes [1] exhibits a continuous freezing transition,whereas hard spheres possess a first order freezing transition. We introduce the model of parallelhard spherocubes, a class of colloidal shapes characterized by the cube parameter q that describesthe continuous deformation from parallel hard cubes (q = 1) to hard spheres (q = 0). Theextended-deconvolution fundamental measure theory [2] is used as well as Monte Carlo andevent-driven molecular dynamics simulations to determine the phase boundaries. The qualitativechange from continuous freezing to first order freezing is analyzed with respect to the shape ofthe spherocubes. The continuous freezing is found to be persistence for cubes with finite rounding(q < 1). We present a phase diagram of packing fraction and the cube parameter q, discussdeviations between theory and simulations and observe an anomalous high vacancy concentration(10%) in the solid phase. Furthermore a new stable crystalline structure corresponding to asheared simple cubic phase is found.[1] Y. Martínez-Ratón, J. A. Cuesta, J. Chem. Phys. 111, 317 (1999).[2] H. Hansen-Goos, K. Mecke, J. Phys. Cond. Matter 22, 364107 (2010).187