On a theoretical analysis on the influence of non-uniformity of the order parameter on the surface energy in nematics

Recently Pikin and Terent'ev have analysed the influence of the non-uniformity of the order parameter on the measured value of the surface cohesion energy in nematic liquid crystals (1988, Sov. Phys. Crystallogr., 33, 641). We argue that since the mathematical problem is ill-posed, the analysis has to be revised. In particular, quadratic terms in the second derivatives of the deformation angle and the order parameter should be taken into account.