Molecular shape and flexoelectricity

TL;DR

This study uses Monte Carlo simulations to explore how molecular shape influences flexoelectric properties in liquid crystal phases, revealing shape-dependent variations in splay and bend coefficients.

Contribution

It introduces a simulation-based analysis linking molecular wedge shape and intermolecular potential to flexoelectric coefficients in liquid crystals.

Findings

Negligible flexoelectric coefficients in isotropic phase.

Shape influences splay coefficient magnitude and sign.

Intermolecular potential properties affect flexoelectric response.

Abstract

We performed Monte Carlo simulations of systems of wedge-shaped objects formed from Gay-Berne ellipsoids joined to Lennard-Jones spheres. We studied two different wedge shapes, one more asymmetric than the other. The bend and splay flexoelectric coefficients were measured in the isotropic and smectic phases using linear response theory, and found to be negligibly small in the isotropic phase. We found a close connection between the properties of the intermolecular potential and the flexoelectric coefficients measured in the smectic phase. In particular, we found negligible bend coefficients for both shapes and a larger magnitude of the splay coefficient for the more prominent wedge, in accord with Meyer's original mechanism for flexoelectricity. The less prominent wedge produced a splay flexoelectric coefficient with the opposite sign due to the attractive tail of the intermolecular potential and the relative narrowness of the molecular head.