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Nematic and smectic ordering in a system of two-dimensional hard zigzag particles
Szabolcs Varga1, Péter Gurin, Julio C Armas-Pérez
1Institute of Physics, University of Pannonia, P.O. Box 158, Veszprém H-8201 Hungary. vargasz@almos.vein.hu
The Journal of Chemical Physics
|November 18, 2009
Summary
The molecular shape of hard zigzag particles significantly impacts their phase transitions. Increasing tail length and bent angle destabilizes the nematic phase but enhances smectic phase stability.
Area of Science:
- Thermodynamics and statistical mechanics of condensed matter systems.
- Phase transitions in two-dimensional systems.
- Soft matter physics and molecular modeling.
Background:
- Understanding molecular ordering is crucial for designing materials with specific properties.
- Hard particle models provide fundamental insights into phase behavior.
- Onsager theory is a powerful tool for analyzing liquid crystal phase transitions.
Purpose of the Study:
- To investigate the orientational and positional ordering of hard zigzag particles in two dimensions.
- To determine the factors influencing isotropic-nematic and nematic-smectic phase transitions.
- To compare theoretical predictions with simulation data.
Main Methods:
- Application of Onsager theory for analytical calculations.
- Investigation of transition densities for phase changes.
- Comparison with Monte Carlo (MC) simulation data.
Main Results:
- Molecular shape critically affects nematic and smectic phase stability.
- Hard needle limit favors isotropic-nematic transition.
- Increased tail length and bent angle destabilize nematic but stabilize smectic phases.
- Zigzag particles form tilted, layered structures with semi-ideal gas behavior within layers.
Conclusions:
- The stability of liquid crystalline phases in hard zigzag systems is highly sensitive to molecular geometry.
- Onsager theory accurately predicts phase behavior, aligning well with MC simulations.
- Layered packing in zigzag systems optimizes excluded volume interactions.
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