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Characteristics of Liquid Crystal Near a Flat Surface Using EES Potential

Amini Dehkordi, Bahareh | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54869 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Ejtehadi, Mohammad Reza
  7. Abstract:
  8. The study of the interaction between ellipsoid particles and the flat wall is the basis for understanding phenomena such as the passage of colloidal particles through the membrane and the order resulting from the presence of the wall in liquid crystals. Previous studies on liquid crystal systems confined between two walls have shown that topological constraints and the surface interaction of particles with the wall change the order behavior and create a surface layer near them. The thickness of this surface layer is about a few molecules, and this helps to achieve the result observed in the laboratory, in computer simulations. LAMMPS software is one of the most powerful codes available for molecular dynamics simulations and is very suitable for parallel simulations. In LAMMPS, the potential for interaction between ellipses, such as the Gay-Berne and RE_squared potentials, is predefined to simulate liquid crystals, while the potential between the ellipse and the wall was non-existent.One of the most important objectives of this dissertation is to add the exact interaction potential between the infinitely thick wall and the liquid crystal ellipsoids, ie the EES potential to LAMMPS for use in simulations involving liquid crystal molecules adjacent to the flat wall. In the following, the results of molecular dynamic simulation of a system including uniaxial liquid crystal ellipsoids between two unstructured flat walls are presented. Particle interaction of RE-Squared type and EES type particle-wall interaction Taken. The simulation results show that the walls create a surface layer in their vicinity. The order parameter profile and particle orientation between the two walls are presented and compared with previous works.
     

  9. Keywords:
  10. Liquid Crystal ; Molecular Dynamics ; Biaxial Ellipsoids ; Flat Wall ; Exact Ellipsoid-Substrate Interaction (EES)Potential ; RE-Squared Potential ; LAMMPS Software

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