TITLE:
Dynamics of a ±1/2 Defect Pair in a Confined Geometry
AUTHORS:
Lixia Lu, Zhidong Zhang
KEYWORDS:
±1/2 Defect Pair, Dynamics, Stable Existence, Confined Geometry
JOURNAL NAME:
Journal of Modern Physics,
Vol.5 No.18,
December
25,
2014
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.