Regensburg 2019 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 17: Statistical Physics (General) I

DY 17.5: Talk

Tuesday, April 2, 2019, 11:00–11:15, H19

Isotropic-anisotropic phase transition in a three-dimensional lattice model of sticky rods — •Paul Quiring, Miriam Klopotek, and Martin Oettel — Institute for applied Physics, Theoretical and Computational Soft Matter/Nano-Science and Experimental Colloidal Physics, Tübingen, Germany

We investigate the isotropic-anisotropic phase transition in a three-dimensional lattice model of 1x1xL-sized hard rods with nearest-neighbor attractions using grand-canonical Monte Carlo simulations. We find that the topology of the phase diagram strongly depends on the rod length L.

For higher temperatures and L>4, we generally find a very weak first order isotropic-nematic transition as in the corresponding system with no attractions [1]. There is no appreciable widening for increasing attractions. For L=8 and decreasing temperature, this transition line ends in a quasi-tricritical point, below which there is a first-order transition between an isotropic vapor and a nematic liquid.

For L=5, the critical point for the liquid-vapor transition between isotropic states is not affected. The nematic order is of ``layered-disordered'' type, i.e. one of the three directions is suppressed. The line of isotropic-nematic transitions presumably ends in a critical endpoint on the liquid side of the binodal.

[1] A. Gschwind, M. Klopotek, Y. Ai und M. Oettel, ``Isotropic-nematic transition for hard rods on a three-dimensional cubic lattice'', Physical Review E, Bd. 96, Nr. 1, S. 012 104, 2017.