Soft Condensed Matter, Biological Physics Experiment & Statistical Physics Seminars

Highly size asymmetrical fluid mixtures arise in a variety of physical contexts, most notably in suspensions of colloidal particles to which much smaller particles have been added in the form of polymers or nanoparticles. Conventional schemes for simulating models of such systems are hamstrung by the difficulty of relaxing the large species in the presence of the small one. In this talk I will describe how the rejection-free geometrical cluster algorithm of Liu and Luijten [PRL 92, 035504 (2004)] can be embedded within a restricted Gibbs ensemble in order to facilitate efficient and accurate studies of fluid phase behaviour of highly size asymmetrical mixtures. After providing a description of the algorithm, I shall summarize the bespoke analysis techniques of Ashton et al [JCP 132, 074111 (2010)] that permit accurate estimates of coexisting densities and critical point parameters. The methods are applied to study the liquid-vapor phase diagram of a particular mixture of Lennard-Jones particles having a 10:1 size ratio. The results reveal qualitatively different behaviour to that expected from the standard depletion picture.