The isotropic-to-nematic phase transition in hard helices: theory and simulation

TL;DR

This paper explores how the shape of hard helical particles influences their phase transition from isotropic to nematic, using theoretical and simulation methods to compare with other particle shapes.

Contribution

It provides new insights into the phase behavior of helical particles, highlighting differences from spherocylinder systems and assessing the accuracy of Onsager theory.

Findings

Helical parameters significantly influence phase behavior.

Onsager theory diverges from simulations for high helicity.

Modified Parsons-Lee rescaling partially accounts for non-convexity.

Abstract

We investigate the isotropic-to-nematic phase transition in systems of hard helical particles, using Onsager theory and Monte Carlo computer simulations. Motivation of this work resides in the ubiquity of the helical shape motif in many natural and synthetic polymers, as well as in the well known importance that the details of size and shape have in determining the phase behaviour and properties of (soft) condensed matter systems. We discuss the differences with the corresponding spherocylinder phase diagram and find that the helix parameters affect the phase behaviour and the existence of the nematic phase. We find that for high helicity Onsager theory significantly departs from numerical simulations even when a modifed form of the Parsons-Lee rescaling is included to account for the non-convexity of particles.