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arXiv · 1507.01682

Soft-core particles freezing to form a quasicrystal and a crystal-liquid phase

A. J. Archer·A. M. Rucklidge·E. Knobloch
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Abstract

Systems of soft-core particles interacting via a two-scale potential are studied. The potential is responsible for peaks in the structure factor of the liquid state at two different but comparable length scales, and a similar bimodal structure is evident in the dispersion relation. Dynamical density functional theory in two dimensions is used to identify two novel states of this system, the crystal-liquid state, in which the majority of the particles are located on lattice sites but a minority remains free and so behaves like a liquid, and a 12-fold quasicrystalline state. Both are present even for deeply quenched liquids and are found in a regime in which the liquid is unstable with respect to modulations on the smaller scale only. As a result the system initially evolves towards a small scale crystal state; this state is not a minimum of the free energy, however, and so the system subsequently attempts to reorganize to generate the lower energy larger scale crystals. This dynamical process generates a disordered state with quasicrystalline domains, and takes place even when this large scale is linearly stable, i.e., it is a nonlinear process. With controlled initial conditions a perfect quasicrystal can form. The results are corroborated using Brownian dynamics simulations.

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A. J. Archer, A. M. Rucklidge, E. Knobloch. 2015-07-07. Soft-core particles freezing to form a quasicrystal and a crystal-liquid phase. https://doi.org/10.1103/physreve.92.012324

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