arXiv subjects

Juan Pedro Ramírez González

Publications and source records attributed to Juan Pedro Ramírez González.

3 recordsLinked to original sources

arXiv2024

Non-nematicity of the filamentary phase in systems of hard minor circular arcs

This work further investigates an aspect of the phase behavior of hard circular arcs, whose phase diagram has been recently calculated by Monte Carlo numerical simulations: the non-nematicity of the filamentary phase that hard minor circular arcs form. Both second-virial density-functional theory and further Monte Carlo numerical simulations find that the positional one-particle density function is undulate in the direction transverse to the axes of the filaments while further Monte Carlo numerical simulations find that the mobility of the hard minor circular arcs across the filaments occurs via a mechanism reminiscent of the mechanism of diffusion in a smectic phase: the filamentary phase is not a {``modulated'' [``splay(-bend)'']} nematic phase.

cond-mat.soft↗

arXiv2021

Phase behavior of hard circular arcs

By using Monte Carlo numerical simulation, this work investigates the phase behavior of systems of hard infinitesimally-thin circular arcs, from an aperture angle $θ\rightarrow 0$ to an aperture angle $θ\rightarrow 2 π$, in the two-dimensional Euclidean space. Except in the isotropic phase at lower density and in the (quasi)nematic phase that solely forms for sufficiently small values of $θ$ and at intermediate values of density, in the other phases that form, including the isotropic phase at higher density, hard infinitesimally-thin circular arcs auto-assemble to form clusters. These clusters are either filamentous, for smaller values of $θ$, or roundish, for larger values of $θ$. Provided density is sufficiently high, the filaments lengthen, merge and straighten to finally produce a filamentary phase while the roundels compact and dispose themselves with their centers of mass at the sites of a triangular lattice to finally produce a cluster hexagonal phase.

cond-mat.soft↗

arXiv2020

Dense packings of hard circular arcs

This work investigates dense packings of congruent hard infinitesimally--thin circular arcs in the two-dimensional Euclidean space. It focuses on those denotable as major whose subtended angle $θ\in \left ( π, 2π\right ]$. Differently than those denotable as minor whose subtended angle $θ\in \left [0, π\right]$, it is impossible for two hard infinitesimally-thin circular arcs with $θ\in \left ( π, 2π\right ]$ to arbitrarily closely approach once they are arranged in a configuration, e.g. on top of one another, replicable ad infinitum without introducing any overlap. This makes these hard concave particles, in spite of being infinitesimally thin, most densely pack with a finite number density. This raises the question as to what are these densest packings and what is the number density that they achieve. Supported by Monte Carlo numerical simulations, this work shows that one can analytically construct compact closed circular groups of hard major circular arcs in which a specific, $θ$-dependent, number of them (anti-)clockwise intertwine. These compact closed circular groups then arrange on a triangular lattice. These analytically constructed densest-known packings are compared to corresponding results of Monte Carlo numerical simulations to assess whether they can spontaneously turn up.

cond-mat.soft↗