25 research outputs found
Design of two-dimensional particle assemblies using isotropic pair interactions with an attractive well
Using ground-state and relative-entropy based inverse design strategies,
isotropic interactions with an attractive well are determined to stabilize and
promote as- sembly of particles into two-dimensional square, honeycomb, and
kagome lattices. The design rules inferred from these results are discussed and
validated in the dis- covery of interactions that favor assembly of the highly
open truncated-square and truncated-hexagonal lattices.Comment: 11 pages, 5 figures and supplemental materia
Origin and Detection of Microstructural Clustering in Fluids with Spatial-Range Competitive Interactions
Fluids with competing short-range attractions and long-range repulsions mimic
dispersions of charge-stabilized colloids that can display equilibrium
structures with intermediate range order (IRO), including particle clusters.
Using simulations and analytical theory, we demonstrate how to detect cluster
formation in such systems from the static structure factor and elucidate links
to macrophase separation in purely attractive reference fluids. We find that
clusters emerge when the thermal correlation length encoded in the IRO peak of
the structure factor exceeds the characteristic lengthscale of interparticle
repulsions. We also identify qualitative differences between the dynamics of
systems that form amorphous versus micro-crystalline clusters.Comment: 6 pages, 5 figure
Treating random sequential addition via the replica method
While many physical processes are non-equilibrium in nature, the theory and
modeling of such phenomena lag behind theoretical treatments of equilibrium
systems. The diversity of powerful theoretical tools available to describe
equilibrium systems has inspired strategies that map non-equilibrium systems
onto equivalent equilibrium analogs so that interrogation with standard
statistical mechanical approaches is possible. In this work, we revisit the
mapping from the non-equilibrium random sequential addition process onto an
equilibrium multi-component mixture via the replica method, allowing for
theoretical predictions of non-equilibrium structural quantities. We validate
the above approach by comparing the theoretical predictions to numerical
simulations of random sequential addition.Comment: 32 pages, 3 figure
Assembly of particle strings via isotropic potentials
Assembly of spherical colloidal particles into extended structures, including
linear strings, in the absence of directional interparticle bonding
interactions or external perturbation could facilitate the design of new
functional materials. Here, we use methods of inverse design to discover
isotropic pair potentials that promote the formation of single-stranded,
polydisperse strings of colloids "colloidomers" as well as size-specific,
compact colloidal clusters. Based on the designed potentials, a simple model
pair interaction with a short-range attraction and a longer-range repulsion is
proposed which stabilizes a variety of different particle morphologies
including (i) dispersed fluid of monomers, (ii) ergodic short particle chains
as well as porous networks of percolated strings, (iii) compact clusters, and
(iv) thick cylindrical structures including trihelical Bernal spirals
Communication: From close-packed to topologically close-packed: Formation of Laves phases in moderately polydisperse hard-sphere mixtures
Particle size polydispersity can help to inhibit crystallization of the hard-sphere fluid into close-packed structures at high packing fractions and thus is often employed to create model glass-forming systems. Nonetheless, it is known that hard-sphere mixtures with modest polydispersity still have ordered ground states. Here, we demonstrate by computer simulation that hard-sphere mixtures with increased polydispersity fractionate on the basis of particle size and a bimodal subpopulation favors the formation of topologically close-packed C14 and C15 Laves phases in coexistence with a disordered phase. The generality of this result is supported by simulations of hard-sphere mixtures with particle-size distributions of four different forms.This research was partially supported by the Welch Foundation (No. F-1696) and by the National Science Foundation through the Center for Dynamics and Control of Materials: an NSF MRSEC under Cooperative Agreement No. DMR-1720595.Center for Dynamics and Control of Material