Orientational fluctuations and pseudo-casimir force in confined nematic liquid crystals

Our theoretical studies of fluctuations in the vicinity of phase and struct ural transitions and the fluctuation-induced force in two model confined ne matic liquid crystals are briefly reviewed. We focus on the paranematic pha se characterized by substrate-stabilized wetting layer and on nematic films frustrated by competing surface fields. Depending on temperature, anchorin g strengths, and frustration, the fluctuation-induced force can be either s hort- or long-range, either attractive or repulsive, and it exhibits a pret ransitional increase.