Disorientation-induced disordering at a nematic-liquid-crystal–solid interface

To explain the observed deviation from the Rapini-Papoular surface energy of nematic-liquid-crystals, we propose a model of the form Tr[(Qᵢⱼ-Q₀ᵢⱼ{)}²$] (${Q}ᵢⱼ$ is the quadrupolar order parameter of the nematic-liquid-crystal and ${Q}₀ᵢⱼa quadrupolar surface field). For a broken anchoring, this model predicts a surface order decrease ΔS3/2(ξ/d){S}Bwhere ξ and d are the coherence and surface extrapolation lengths of the nematic liquid crystal and{S}B$ is the bulk order parameter. A quantitative check is presented on planar anchoring of various strengths and temperatures.