1,270 research outputs found
Hopping and microscopic dynamics of ultrasoft particles in cluster crystals
We have investigated the slow dynamics of ultrasoft particles in crystalline
cluster phases, where point particles interact through the generalized
exponential potential u(r) = \epsilon \exp[-(r/\sigma)^n], focusing on the
cluster fcc phase of this model with n=4. In an effort to elucidate how the
mechanisms of mass transport depend on the microscopic dynamics and in order to
mimic a realistic scenario in a related experiment we have performed molecular
dynamics, Brownian dynamics, and Monte Carlo simulations. In molecular dynamics
simulations the diffusion of particles proceeds through long-range jumps,
guided by strong correlations in the momentum direction. In Monte Carlo and
Brownian dynamics simulations jump events are short-ranged, reflecting the
purely configurational nature of the dynamics. In contrast to what was found in
models of glass-forming liquids, the effect of Newtonian and stochastic
microscopic dynamics on the long-time relaxation cannot be accounted for by a
temperature-independent rescaling of the time units. From the obvious
qualitative discrepancies in the short time behavior between the three
simulation methods and the non-trivial difference in jump length distributions,
long time relaxation, and dynamic heterogeneity, we learn that a more complex
modeling of the dynamics in realistic systems of ultrasoft colloids is
required.Comment: 12 pages, 18 figures, added results of Brownian dynamics simulation
- …