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

Fri 911:10-14:00P4.37Diffusion of ultrasoft particles in cluster crystals in thepresence of a solventMarta Montes Saralegui, 1 Arash Nikoubashman, 1 and Gerhard Kahl 11 Vienna University of Technology, Institute of Theoretical Physics and CMS, WiednerHauptstrasse 8-10 1040, Vienna, AustriaRecently, the microscopic dynamics in cluster crystals has attracted strong attention, and phenomena,such as activated hopping and finite long-time diffusivity, have been observed [1, 2], whichdistinguish them distinctly from their hardcore counterparts. These ultrasoft systems have beeninvestigated thoroughly by the means of Molecular Dynamics, Brownian Dynamics and MonteCarlo simulations [1]. However, so far explicit hydrodynamic interactions caused by the solventhave been neglected. In this work, we address this issue by employing Multi-Particle CollisionalDynamics simulations and discover that hydrodynamics do play a crucial role in the microscopicdynamics of these systems: the solvent acts as a buffer between the lattice sites and jump events ofparticles are constrained to the nearest neighbor sites, reflecting the purely configurational natureof the dynamics. Furthermore, we find that the hopping processes can be described by standardrandom walks. They are completely suppressed as the system temperature is decreased and as thethermal energy falls below the activation energy.[1] D. Coslovich, L. Strauss, and G. Kahl, Soft Matter 7, 2127 (2011)[2] A. J. Moreno and C. N. Likos, Phys. Rev. Lett. 99, 107801 (2007)37