PhysRevE.92.012324.pdf (3.91 MB)
Download fileSoft-core particles freezing to form a quasicrystal and a crystal-liquid phase
journal contribution
posted on 2015-09-09, 09:31 authored by Andrew ArcherAndrew Archer, Alastair M. Rucklidge, Edgar KnoblochSystems 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 unusual states of this system: a 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.
Funding
The work of E.K. was supported in part by the National Science Foundation under Grant No. DMS-1211953.
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