Last modified:
April 06 2018 10:07

Current Top Issues

Self Assembly of Janus particles under shear

In the paper, the effect of shear flow on the self-assembly behavior of Janus particles is investigated in the regime of micelles formation. Under quiescent conditions, the colloids form spherical aggregates of different sizes, where the attractive hemispheres are directed towards the core and the repulsive caps are exposed to the solvent. When a strong shear is applied, the micelles disaggregate. Nonetheless, an intermediate shear rate regime is found, where the balance between rearrangement and dissociation favors the growth of the aggregates. Moreover, a small shear rate can push the system to form mainly icosahedral micelles that are the most stable due to their high symmetry.

Published and featured as cover article in Soft Matter 11, 4767 (2015)

Interface pinning method

An important aspect of computational condensed matter physics is the computation of phase diagrams of model systems. The thermodynamically stable phase is the one with the lowest Gibbs free energy. "Interface pinning" is a method where the Gibbs free energy differences between phases is computed directly in a single equilibrium simulation. This is done by applying an artificial external field that biases the system towards two-phase configurations. The Gibbs free energy difference is then determined from the average force that the field exert on the system. In addition, the method gives information about the interface between the phases.

Published in J. Chem. Phys. 139, 104102 (2013)

Activated hopping in ultrasoft cluster crystals

Ultrasoft potentials (potentials bounded at r=0) can, under the appropiate conditions, crystalize into a multiple occupancy crystal. This novel kind of material has many surprising characteristics. Among them, activated hopping is the main mass transport mechanism. A particle can be thermally activated and gain sufficient energy to abandone its host cluster and hop around the crystal until it finds a new hosting positions. In our contribution we show how normal Molecular Dynamics (MD) simulations overestimate the scope of this mechanism, and how a faithful inclusion of the hydrodynamic interactions with the solvent via a suitable simulation technique (Multi-Particle Collision Dynamics, MPCD) dramatically shortens the length and the amount of the trajectories followed by the hopping particles.

Published in J. Phys.: Condens. Matter 25, 195101 (2013)

Typical trajectories in the same setup for a hopping particle when, (left) in an MD simulation and (right) in an MPCD simulation.

Contact Information

Institut für Theoretische Physik
Technische Universität Wien
Wiedner Hauptstrasse 8-10/136
A-1040 Wien, Austria
Tel : +43 1 5880113632
Fax : +43 1 5880113699
E-mail : gkahl(at)