Novel elastic response in twist-bend nematic models.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Soft Matter Physics

Background:

• Bent-shaped liquid crystals display unique mesostructures and anisotropic elastic constants.
• Theories predict a negative bend elastic constant (K3) at the nematic-twist-bend (NTB) transition, but experimental evidence is lacking.
• Experimentally, the bend elastic constant shows a non-monotonic temperature dependence near the NTB transition.

Purpose of the Study:

• To investigate the molecular mechanisms governing the elastic response of bent-shaped liquid crystals.
• To understand the unusual temperature dependence of Frank-Oseen elastic constants in the nematic and NTB phases.
• To elucidate the behavior of the bend elastic constant near the nematic to twist-bend nematic transition.

Main Methods:

• Utilized density of states algorithms within Monte Carlo simulations.
• Employed a modified Lebwohl-Lasher model incorporating bent-shaped interactions.
• Analyzed the Frank-Oseen elastic constants and their temperature dependencies.

Main Results:

• The study provides insights into the molecular origins of exotic elastic behaviors in bent liquid crystals.
• Simulations reveal the complex interplay of molecular shape and interactions influencing elastic properties.
• The temperature dependence of the bend elastic constant, including its dip near the NTB transition, is analyzed.

Conclusions:

• The findings contribute to understanding the fundamental physics of bent-shaped liquid crystals.
• This work bridges theoretical predictions and experimental observations regarding the NTB phase and elastic constants.
• The simulation approach offers a valuable tool for studying complex liquid crystal phases.