Impact of ageing on structure of random sequentialadsorption packings of discorectangles

Abstract

The ageing processes in the systems of elongated particles (discorectangles) adsorbed on a plane was studied numerically. An off-lattice model with continuous positional and orientational degrees of freedom was tested. The initial jammed state was produced using the random sequential adsorption (RSA) model. The transition from the jammed to equilibrium states were performed via translational and rotational Brownian motions. An aspect ratio of the particles (length-to-width ratio) was varied within the range $\varepsilon=1-12$. At $\varepsilon < 10$ the relaxation into the isotropic state %with $S=0$ was always observed. In the intermediate range, $10 \le \varepsilon \le 11$, the relaxation transition into the states with ordered domains was observed. Particularly, for $ \varepsilon=10$ this transition was related with significant finite size scaling effects. For particles with $\varepsilon=12$ formation of the large scale quasi-nematic domains and unlimited domain growth was observed. The impact of the relaxation on the domain structure, porosity, percolation connectivity and tracer particle diffusion in such barrier systems was also discussed.