Phase behavior of polarizable spherocylinders in external fields

Area of Science:

• Physics
• Materials Science
• Computational Chemistry

Background:

• Applied electric fields significantly alter properties of polarizable molecular systems.
• Rod-shaped molecules exhibit complex, sometimes surprising, field-induced behaviors, such as negative electric birefringence in polyelectrolyte solutions.

Purpose of the Study:

• Investigate the interplay between shape anisotropy and field-induced anisotropy in polarizable soft spherocylinders.
• Explore the formation of novel structures and phase diagrams under external electric fields.
• Compare the behavior of systems with induced dipoles versus permanent dipoles.

Main Methods:

• Molecular dynamics simulations of polarizable soft spherocylinders in an electric field.
• Modeling the limit of infinitely anisotropic polarizability.
• Accounting for mutual induction effects between particles.

Main Results:

• Discovery of a novel crystalline structure, designated K(2), at high electric field strengths.
• K(2) phase formation is driven by interactions between induced dipoles.
• A polar nematic phase exists between the hexagonal close-packed crystal and K(2) phases at high pressures.
• Qualitatively similar behavior observed for spherocylinders with permanent dipoles under strong external field coupling.

Conclusions:

• Electric fields can induce novel crystalline structures in anisotropic soft matter through dipole-dipole interactions.
• The phase behavior of polarizable spherocylinders is rich, featuring distinct crystalline and liquid crystalline phases.
• Induced dipole interactions play a crucial role in self-assembly and structure formation in external fields, mirroring effects seen with permanent dipoles.