Glassy dynamics of dense particle assemblies on a spherical substrate

Abstract

We study by molecular dynamics simulation a dense one-component system of particles confined on a spherical substrate. We more specifically investigate the evolution of the structural and dynamical properties of the system when changing the control parameters, the temperature and the curvature of the substrate. We find that the dynamics become glassy at low temperature, with a strong slowdown of the relaxation and the emergence of dynamical heterogeneity. The prevalent local 6-fold order is frustrated by curvature and we analyze in detail the role of the topological defects in the statics and the dynamics of the particle assembly.

Cooperatively rearranging regions change shape near the mode-coupling crossover for colloidal liquids on a sphere

“…Moreover, the dynamics was also highly cooperative with the mobile particles being spatially clustered 36 . Further, unlike in simulations of liquids of monodisperse particles on S 2 , where dynamical heterogeneities were found to be largely localized at topological defects at low temperatures 22 , the heterogeneities in our system appear at spatially random locations and are reminiscent of standard supercooled liquid dynamics in Euclidean space 33 . Next, we identified the top 10% of the most-mobile particles over t * and clustered them if their centers were within 1.4 σ of each other.…”

“…We now turn our attention to dynamics. We first computed the self-intermediate scattering function which on a sphere is defined as 9 , 22 . Here, P k R is the Legendre polynomial with k R being rounded-off to the nearest-integer, k is the wavevector corresponding to the first peak of g ( s ), M is the number of particles and Δ s j (0, t ) is the geodesic displacement of particle j over time t .…”

“…MW fluctuations are also strongly system size-dependent and their effects diminish systematically on reducing system size 17 – 21 . In fact, for liquids on closed surfaces, like S 2 , system size and curvature effects are intertwined 22 . The role of MW fluctuations on the dynamics of liquids on curved surfaces, let alone on S 2 , is not known.…”

Entropic Effects of Interacting Particles Diffusing on Spherical Surfaces

“…To study the dynamic behavior of each system, Molecular Dynamics simulations were performed in the canonical assembly (NVT) for a total of N 1000 particles embedded in the spherical surface, with a surface density given by ρ p ( N/A) 0.92. The R and ρ p values were taken for compatibility with previous studies by Vest et al [45][46][47]. The system was placed in a thermal bath at a temperature T p 1.0 set constant by using the isokinetic method; the integration of the equations of motion was carried out using the velocity-Verlet algorithm [48], with the restriction f i (r i ) |r i | 2 − R 2 0 (see Ref.…”

A variational mean-field study of clusterization in a zero-temperature system of soft-core bosons

“…Spherical boundary conditions are often employed in simulations as a means to discourage crystalline ordering at high density (as is well known, triangular order is frustrated on a sphere [17][18][19][20]). In practice, the curvature imposes a distinct excess of fivefold disclinations over sevenfold ones, which considerably complicates the search for optimal packings, even for small radii.…”