Nematic phases from nearly spherical mesogens: applying the approximate non-conformal (ANC) theory

Abstract

A coarser model for the Gay-Berne mesogen is developed using the interaction potential from the Approximate Non-Conformal (ANC) theory. The ANC potential contains both repulsive and attractive contributions. We modify intermolecular attractions by conditioning them with a Hess-Su orientation-dependent term. This imparts an anisotropic contribution to the energy of the system. The softness parameter s of the ANC potential is probed to qualitatively identify a threshold capable of sustaining a nematic phase. We construct phase diagrams for each value of s from molecular dynamics simulations and characterise bulk samples to outline phase regions. We find that a softness parameter $s\sim 0.6$ or higher supports the emergence of a nematic phase. The stability of the nematic region is enhanced as $s\to 1$, corresponding to the conventional Lennard-Jones interaction. The stability of the nematic phase for nearly-spherical mesogens with increasing s leads to a gradual loss in spherical symmetry despite no imposed shape anisotropy. Thus, the energy anisotropy becomes more pronounced and is capable of prompting the emergence of the nematic phase in this model.

GRAPHICAL ABSTRACT

Keywords:

• Phase diagrams
• nematic
• mesogen
• anisotropy
• liquid crystals

Acknowledgments

JAMR gratefully acknowledges the support provided through grants UNAM-DGAPA-PAPIIT IN114721, LANCAD-UNAM-DGTIC-276, and LANCAD-UNAM-DGTIC-247, in addition to the generous computing time provided by the Laboratorio de Supercómputo y Visualización en Paralelo at UAMI (LSVP-UAMI).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

JMV and AJRR are thankful for the financial support received through a CONACYT graduate fellowship (No. 947695 and 1234731).