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

Wed 711:10-14:00P5.115A new model for tetrahedral colloidal particlesGianmarco Munao, 1 Dino Costa, 1 Francesco Sciortino, 2 and Carlo Caccamo 11 Università di Messina, Viale F. Stagno d’Alcontres 31, 98166, Messina, Italy2 Università di Roma ”La Sapienza”, Roma, ItalyIn the present work, we propose a new model for tetrahedral colloidal particles, in which the highdirectionality of the interactions is connected with the molecular geometry. The model is investigatedby means of different Monte Carlo simulation techniques and the reference interaction sitemodel (RISM) theory of molecular fluid. Both theoretical and simulation results provide a pictureof the model which shows the main features typical of a valence limited system, like the smallvalue of critical density and the presence of a region in the phase diagram in which well definednetworks may be developed, avoiding the crystallization. In particular, simulations and theory signalthe onset, at sufficiently low temperatures, of two different tetrahedral molecular arrangements,with a more open topology progressively giving place to a fully bonded one as the temperature decreases.The RISM theory reproduces the splitting of the static structure factor at low temperatures,a feature related to the onset of the tetrahedral ordering. Less accurate predictions are obtained forthe liquid-vapour coexistence and the short- range correlations.115