Lixia Lu^1,2,3, Zhidong Zhang^3*

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¹ Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, China.
² University of Chinese Academy of Sciences, Beijing, China.
³ School of Science, Hebei University of Technology, Tianjin, China.
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Abstract: This paper investigated the dynamics of a dipole of ±1/2 parallel wedge disclination lines in a confined geometry, based on Landau-de Gennes theory. The behavior of the pair depends on the competition between two kinds of forces: the attractive force between the two defects, aggravating the annihilation process, and the anchoring forces coming from the substrates, inhibiting the annihilation process. There are three states when the system is equilibrium, divided by two critical thicknesses dc1 and dc2 (existing when r0≤15ξ, r0 is the initial distance between the two defects), both changing linearly with r0. When the cell gap d＞dc1, the two defects coalesce and annihilate. The dynamics follows the function of r∝(t0-t)α during the annihilation step when d is sufficiently large, relative to r0, where r is the relative distance between the pair and t0 is the coalescence time. α decreases with the decrease of d or the increase of r0. The annihilation process has delicate structures: when r0≤15ξ and d＞dc2 or r0＞15ξand d＞dc1, the two defects annihilate and the system is uniaxial at equilibrium state; when r0≤15ξ and dc2＞d＞dc1, the two defects coalesce and annihilate, and the system is not uniaxial, but biaxial in the region where the defects collide. When d≤dc1, the defects can be stable existence.

Keywords: ±1/2 Defect Pair, Dynamics, Stable Existence, Confined Geometry

Cite this paper: Lu, L. , Zhang, Z. (2014) Dynamics of a ±1/2 Defect Pair in a Confined Geometry. Journal of Modern Physics, 5, 2080-2088. doi: 10.4236/jmp.2014.518204.

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