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Nonlinear theory of defects in nematic liquid crystals; phase transition and flow phenomena. (English) Zbl 0703.35173

The author deals mainly with the question of defect lines in nematic crystals, i.e. lines along which the optical director n is singular. After a long (but necessary) introductory section he discusses how to modify the energy functional in the Oseen-Frank model in order to cope with the difficulty arising from its possible divergence. The basic idea is to introduce a divergence-free field Q, playing the role of the order parameter of Landau’s theory: \(Q=s(n\otimes n-I/3)\), \(| n| =1\), s being a space-dependent scalar, called the degree of orientation. Q replaces n in the energy integral. Under some simplifying assumptions the problem is reduced to finding a minimizing pair (s,u), \(u=sn\). Existence and Hölder continuity of the solutions are also discussed. The final section is devoted to dynamic models.
Reviewer: A.Fasano

MSC:

35Q99 Partial differential equations of mathematical physics and other areas of application
35A05 General existence and uniqueness theorems (PDE) (MSC2000)
35B05 Oscillation, zeros of solutions, mean value theorems, etc. in context of PDEs
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References:

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