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Computer simulation of apolar bent-core and rodlike molecules
Stephen J Johnston1, Robert J Low, Maureen P Neal
1School of Mathematical and Information Sciences, Coventry University, Coventry, CV1 5FB, United Kingdom.
Summary
Computer simulations reveal how bent-core molecules influence liquid crystal phases. Increasing the molecular bend angle (gamma) generally lowers transition temperatures and alters phase stability, with unique phases observed at specific angles.
Area of Science:
- Materials Science
- Computational Chemistry
- Condensed Matter Physics
Background:
- Bent-core molecules exhibit unique biaxiality and complex phase ordering.
- Understanding molecular shape effects is crucial for designing novel liquid crystal materials.
Purpose of the Study:
- To model the characteristic shape of bent-core molecules.
- To investigate the impact of molecular geometry on liquid crystal mesophase formation using computer simulations.
Main Methods:
- Utilized a two-site Gay-Berne potential model for molecular interactions.
- Systematically varied the angle between interaction sites (180-gamma) from 0 to 70 degrees.
- Performed computer simulations to observe phase transitions and mesophase behavior.
Main Results:
- The rodlike model (gamma=0) exhibited isotropic, nematic, smectic-A, and smectic-B phases.
- Increasing the bend angle (gamma) decreased transition temperatures to ordered phases.
- Nematic phase stability varied, with tilted smectic-B and TGB-like phases observed at specific gamma values (20 and 40 degrees, respectively).
- At gamma=70 degrees, no ordered phase was observed.
Conclusions:
- Molecular geometry significantly influences liquid crystal phase behavior.
- The degree of bending in bent-core molecules dictates the type and stability of observed mesophases.
- Simulation results provide insights into the design principles for advanced liquid crystal materials.