Ground states of ultrasoft particles with attractions: a genetic algorithm approach

Abstract

We analyse in detail the ground-state structure of model systems of athermal star polymers with an additional, tunable attraction that may result from dispersion or depletion forces. To perform a free, unbiased search in the space spanned by the crystal parameters, we employ genetic algorithms, which are enhanced with respect to previous versions in their ability to find stable structures that occupy very narrow basins of attraction in the energy landscape. Application of this method brings about a very large variety of ground states for star polymers with attractions, in particular for the case of intermediate functionalities and strong, short-range attractive forces.

Keywords:

• genetic algorithms
• soft matter
• soft colloids
• statistical mechanics
• phase behaviour

Acknowledgements

The authors thank Julia Fornleitner and Gerhard Kahl (Vienna University of Technology) for helpful discussions. FLV has been supported by the Foundation Blanceflor Boncompagni-Ludovisi, née Bildt. This work is dedicated to Jean-Jacques Weis on the occasion of his 65th birthday.