Condensed Matter Theory

Abstract:

The torque induced between bounding surfaces in nematic liquid crystals due to thermal fluctuations was reported. The existence of Casimir torque due to anisotropy in the shape of the objects immersed in the complex fluid depended on the relative orientation of these objects. The torques were calculated for a simple geometry in the absence of elastic effects. These calculations suggested a direct measure of the torque exerted between two plates at fixed separation and a measure of force as a function of separation for plates at various angles.

Abstract:

Many-body interactions and correlations in coarse-grained descriptions of polymer solutions were studied using Monte Carlo simulations. The effective density dependent two-body potentials that exactly reproduced the pair-correlations between the center of mass (c.m.) of the self avoiding walk polymers were also studied. The results showed that a pair potential cannot simultaneously reproduce the two- and three-body correlations in a system with many-body interactions.

Abstract:

Fluctuation-induced interactions between anisotropic objects immersed in a nematic liquid crystal are shown to depend on the relative orientation of these objects. The resulting long-range "Casimir" torques are explicitly calculated for a simple geometry where elastic effects are absent. Our study generalizes previous discussions restricted to the case of isotropic walls, and leads to new proposals for experimental tests of Casimir forces and torques in nematics.