4 research outputs found
Controlled self-assembly of periodic and aperiodic cluster crystals
Soft particles are known to overlap and form stable clusters that
self-assemble into periodic crystalline phases with density-independent lattice
constants. We use molecular dynamics simulations in two dimensions to
demonstrate that, through a judicious design of an isotropic pair potential,
one can control the ordering of the clusters and generate a variety of phases,
including decagonal and dodecagonal quasicrystals. Our results confirm
analytical predictions based on a mean-field approximation, providing insight
into the stabilization of quasicrystals in soft macromolecular systems, and
suggesting a practical approach for their controlled self-assembly in
laboratory realizations using synthesized soft-matter particles.Comment: Supplemental Material can be obtained through the author's website
at: http://www.tau.ac.il/~ronlif/pubs/ClusterCrystals-Supp.pd
Stability of Quasicrystals Composed of Soft Isotropic Particles
Quasicrystals whose building blocks are of mesoscopic rather than atomic
scale have recently been discovered in several soft-matter systems. Contrary to
metallurgic quasicrystals whose source of stability remains a question of great
debate to this day, we argue that the stability of certain soft-matter
quasicrystals can be directly explained by examining a coarse-grained free
energy for a system of soft isotropic particles. We show, both theoretically
and numerically, that the stability can be attributed to the existence of two
natural length scales in the pair potential, combined with effective three-body
interactions arising from entropy. Our newly gained understanding of the
stability of soft quasicrystals allows us to point at their region of stability
in the phase diagram, and thereby may help control the self-assembly of
quasicrystals and a variety of other desired structures in future experimental
realizations.Comment: Revised abstract, more detailed explanations, and better images of
the numerical minimization of the free energ