Weak Freedericksz transition

Such reformulated boundary conditions will be used in Section 3.6 below in the case of an elementary weak Freedericksz transition. Notice also that wf appearing in the above formulations may be replaced by any applicable total bulk energy density which may also incorporate any relevant magnetic and/or electric energy densities. 

They calculated the coefficients of an expansion of the Kij(S, T) up to fourth order in the order parameter S and the degree of biaxiality T. In case of weak biaxiality Telastic moduli (/= /, m, n)) are predominant and the deformation state may be described satisfactorily with three bulk and one surface elastic constant, as in the uniaxial case. Recently, these three quasi-uni-axial bulk elastic constants of slightly biaxial nematic copolyesteramide have been determined by De Neve et al. [313] from an optical observation of the Freedericksz transition in different geometries. 

Sugimura A, Luckhurst GR, On-Yang Z (1995) Director deformation of a twisted chiral nematic liquid crystal cell with weak anchraing boundaries. Phys Rev E 52(l) 681-689 Torrent MC, Sagues F, Arias F, San Miguel M (1988) Freedericksz transition in a periodic magnetic field. Phys Rev A 38(5) 2641-2649... 

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