Dresden 2011 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 25: Colloids and Complex Liquids I - Structure

CPP 25.8: Talk

Wednesday, March 16, 2011, 12:30–12:45, ZEU 222

Is there a hexatic phase in quasi-2d? — •Nadezhda Gribova, Axel Arnold, and Christian Holm — ICP, Universität Stuttgart, Stuttgart, Germany

A quasi-2d system, a 3d system that is constrained in one of the directions, is expected to combine some characteristic properties both of 2d systems and of 3d systems. One of the most interesting features of 2d systems is the existence of a hexatic phase, an intermediate phase in the liquid-to-solid transition.

The presence of this transition in quasi-2d systems is an open question, and even in 2d systems it is still under discussion. In our work we report a computer simulation study of a Lennard-Jones liquid confined in a narrow slit pore with tunable attractive walls. In order to investigate how the freezing in this system occurs, we perform an analysis using a broad range of order parameters that have been used so far to investigate the existence of the hexatic phase in 2d systems. It turns out, that although some of the parameters indicate that the system goes through a hexatic phase, other parameters exclude it. This shows that to be certain whether a system has a hexatic phase, one needs to study not only a big system, but also several order parameters to check all necessary properties. We observe an intermediate hexatic phase only in the slit with extremely attractive walls and a single layer of particles, i. e. if the system is practically perfectly 2d.