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

Fri 911:10-14:00P3.37Mesophase formation in a system of top-shaped hardmolecules: density functional theory and MC simulationFranz Vesely, 1 Daniel de las Heras, 2 and Szabolcs Varga 31 University of Vienna, Boltzmanngasse 5, A 1090, Vienna, Austria2 Universidade de Lisboa, Lisbon, Portugal3 University of Pannonia, Veszprém, HungaryWe present the phase diagram of a system of mesogenic top-shaped molecules based on theParsons-Lee density functional theory and Monte Carlo simulation. The molecules are modeled asa hard spherocylinder with a hard sphere embedded in its center. It is found that the central sphericalunit destabilizes the nematic with respect to the isotropic phase, while increasing the length ofthe cylinder has the opposite effect. Also, the central hard sphere has a strong destabilizing effecton the smectic A phase, due the inefficient packing of the molecules into layers. For large hardsphere units the smectic A phase is completely replaced by a smectic C structure. The columnarphase is first stabilized with increasing diameter of the central unit, but for very large hard sphereunits it becomes less stable again. The density functional results are in good agreement with thesimulations.37