K-13 TERM AND EFFECTIVE BOUNDARY-CONDITION FOR THE NEMATIC DIRECTOR

We consider the problem of including the divergence term K(13)del[n(de l n)] in the macroscopic theory of a nematic liquid crystal. The orien tation of the bulk director is shown to be determined by the standard Euler Lagrange equation with an effective boundary condition which ass umes a smooth vanishing of the nematic density at the surface and inco rporates additional subsurface deformations. This boundary condition i mplies that, in three dimensions, the K-13 term does not reduce to an anchoring term.