Columnar structures of soft spheres: Metastability and hysteresis

Abstract

Previously we reported on the stable (i.e. minimal enthalpy) structures of soft monodisperse spheres in a long cylindrical channel. Here, we present further simulations, which significantly extend the original phase diagram up to D/d = 2.714 (ratio of cylinder and sphere diameters), where the nature of densest sphere packing changes. However, macroscopic systems of this kind are not confined to the ideal equilibrium states of this diagram. Consequently, we explore some of the structural transitions to be expected as experimental conditions are varied; these are in general hysteretic. We represent these transitions in a stability diagram for a representative case. Illustrative videos are included in the Supplemental Material. arXiv:1805.07673v3 [cond-mat.soft]

Theory of rotational columnar structures of soft spheres

“…1 -horizontally, as in the packing simulations of Ref. [19,20], or vertically, as in the present Rapid Communication.…”

“…These introduce interesting features: They are attributed to finite-size effects, which should be looked for in future experiments. In any such experiments, one should also be aware of the existence of metastability and hysteresis in macroscopic systems, which we have recently explored in a related context [19,20].…”

“…For hard spheres the densest arrangement depends critically on the ratio of D, the cylinder diameter, to d, the sphere diameter, as was found in computer simulations [12][13][14][15][16][17]. Such simulations have also been carried out for the packings of soft spheres [18][19][20].…”

“…The densest hard sphere packings can be classified as either homogeneous (previously called symmetric structure of single phase [13,19,20]) packings or line-slip arrangements; examples of both are shown in the inset of Fig. 1.…”

Densest-Packed Columnar Structures of Hard Spheres: An Investigation of the Structural Dependence of Electrical Conductivity

“…Prominent examples include the application of the face-centered cubic (fcc) and hexagonal close-packed (hcp) structures as models for bulk crystal structures of solids [4] and the application of random close packings as models for bulk amorphous structures of liquids [3,6]. In contrast to these examples for bulk systems, the past few decades have seen an uprising interest in the packings of particles in confined settings, such as those of particles confined within a two-dimensional box [7,8], within a parallel strip [9][10][11][12][13][14], within a spherical container [15,16], within a cylindrical container [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36], onto a cylindrical surface [37], between parallel plates [38][39][40][41][42][43][44][45][46], within a wedge cell [47,48], or within a flexible conta...…”