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Simulation of a System of Biaxial Ellipsoid Liquid Crystals with RE-squared Interaction Potential

Zahedi Ghasemian, Zahra | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42950 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Ejtehadi, Mohammad Reza
  7. Abstract:
  8. Liquid crystals are the type of the matter which show different levels of symmetry and structural properties in between those of a crystalline solid and an isotropic liquid. They can form various phases such as uni- or bi-axial nematics that because of their applications in display technology, have been widely investigated. In this thesis, uniaxial and biaxial ellipsoid liquid crystals have been simulated by using molecular dynamics simulations using LAMMPS simulation software. By control of the density of the system in NVT ensemble, the phase transitions of the systems were investigated. In all the simulations, the mesogens interact with RE-squared coarse grained force field. By calculating the orientational order parameters and radial distribution functions, the phase behaviors of these systems were studied. Our results, in the case of uniaxial ellipsoids, were in good agreement with previous reports, including simulations with Gay-Berne potential, and also RE-squared interacting potential which carried out by EMD simulation software. In the case of oblate biaxial ellipsoids, uniaxial nematic and biaxial nematic phases were observed in all investigated tempratures. For prolate biaxial molecules, in the case of molecules with x = 10:96A , y = 1:99A and z = 0:46A, just for two lower investigated temperatures, the uniaxial nematic and biaxial nematic phases were observed. Nevertheless, in the case of molecules with x = 6:56A , y = 2:28A and z = 0:47A, the biaxial smectic phase was also observed in addition to the two other phases.
  9. Keywords:
  10. Liquid Crystal ; RE-Squared Potential ; Molecular Dynamic Simulation ; Biaxial Ellipsoids ; Biaxial Nematic Phase

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