9 research outputs found
Glass transition of charged particles in two-dimensional confinement
The glass transition of mesoscopic charged particles in two-dimensional
confinement is studied by mode-coupling theory. We consider two types of
effective interactions between the particles, corresponding to two different
models for the distribution of surrounding ions that are integrated out in
coarse-grained descriptions. In the first model, a planar monolayer of charged
particles is immersed in an unbounded isotropic bath of ions, giving rise to an
isotropically screened Debye-H\"uckel- (Yukawa-) type effective interaction.
The second, experimentally more relevant system is a monolayer of negatively
charged particles that levitate atop a flat horizontal electrode, as frequently
encountered in laboratory experiments with complex (dusty) plasmas. A steady
plasma current towards the electrode gives rise to an anisotropic effective
interaction potential between the particles, with an algebraically long-ranged
in-plane decay. In a comprehensive parameter scan that covers the typical range
of experimentally accessible plasma conditions, we calculate and compare the
mode-coupling predictions for the glass transition in both kinds of systems.Comment: 10 pages, 8 figure
Glass-Transition Properties from Hard Spheres to Charged Point Particles
The glass transition is investigated in three dimensions for single and
double Yukawa potentials for the full range of control parameters. For
vanishing screening parameter, the limit of the one-component plasma is
obtained; for large screening parameters and high coupling strengths, the
glass-transition properties crossover to the hard-sphere system. Between the
two limits, the entire transition diagram can be described by analytical
functions. Different from other potentials, the glass-transition and melting
lines for Yukawa potentials are found to follow shifted but otherwise identical
curves in control-parameter space.Comment: 6 pages, 5 figure
Glassy dynamics of Brownian particles with velocity-dependent friction
We consider a two-dimensional model system of Brownian particles in which slow particles are accelerated while fast particles are damped. The motion of the individual particles is described by a Langevin equation with Rayleigh-Helmholtz velocity-dependent friction. In the case of noninteracting particles, the time evolution equations lead to a non-Gaussian velocity distribution. The velocity-dependent friction allows negative values of the friction or energy intakes by slow particles, which we consider active motion, and also causes breaking of the fluctuation dissipation relation. Defining the effective temperature proportional to the second moment of velocity, it is shown that for a constant effective temperature the higher the noise strength, the lower the number of active particles in the system. Using the Mori-Zwanzig formalism and the mode-coupling approximation, the equations of motion for the density autocorrelation function are derived. The equations are solved using the equilibrium structure factors. The integration-through-transients approach is used to derive a relation between the structure factor in the stationary state considering the interacting forces, and the conventional equilibrium static structure factor