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The helical twisting power ␤ M determines the pitch of the chiral nematic phase produced when a nematic liquid crystal is doped with a low concentration of chiral solute molecules. Molecules with large ␤ M values have potential applications in electro-optic displays and in optical data storage. This paper describes a new simulation technique which allows the prediction of both the sign and magnitude of ␤ M. The method employs Monte Carlo simulations of a fully atomistic model of a chiral dopant in the presence of a twisted nematic solvent composed of Gay-Berne particles. Calculations are presented for five different chiral dopants, with results that are in good agreement with existing experimental data.

Monte Carlo simulations have been carried out for an off-lattice model of an amphiphilic polymer at a hydrophobic/hydrophilic interface. The model system consists of a polynorbornene backbone with poly(ethylene oxide) (PEO) grafts modelled atomistically at an idealized interface between hydrophobic and hydrophilic regions, which are represented by external potentials. Results are presented for the distribution of PEO chain ends, and the density of PEO segments perpendicular to the surface. The latter is used to provide predictions for neutron reflectivity profiles normal to the surface as a function of the lateral confinement of the PEO grafts. At low surface coverage the simulation results are found to be in good agreement with experimental neutron scattering results from similar polymers studied at the water/air interface.

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