Barocaloric effect in a Gay-Berne liquid crystal.

A coarse-grained molecular Monte Carlo simulation of the barocaloric effect in a model Gay-Berne liquid crystal is presented, following the so-called indirect approach wherein the caloric response is obtained from thermodynamic arguments applied to the simulated equilibrium relation between pressure, density, and temperature. From simulation, the magnitude of the effect across the isotropic-nematic and nematic-smectic phase transitions is estimated, together with the heat exchanged outside these transitions, in order to assess its potential for novel cooling and heat pumping applications. Under adiabatic conditions, pressure-induced phase transitions are predicted to result in a temperature variation of a few degrees Kelvin.

On the Effects of Different and Populations in Azobenzene Liquid Crystal Elastomers: A Monte Carlo Investigation.

We investigate main-chain liquid crystal elastomers (LCEs) formed by photoresponsive azobenzene units with different populations of and conformers (from fully to fully ). We study their macroscopic properties as well as their molecular organization using extensive Monte Carlo simulations of a simple coarse-grained model where the and conformers are represented by soft-core biaxial Gay-Berne particles with size and interaction energy parameters obtained by fitting a bare bone azobenzene moiety represented at atomistic level. We find that increasing the fraction of conformers, as could be obtained by near-UV irradiation, shifts the nematic-isotropic transition to a lower temperature, consistently with experiment, while generating internal stress in a clamped sample.

The nematic-isotropic transition of the Lebwohl-Lasher model revisited.

We revisited the nematic-isotropic (NI) transition of the Lebwohl-Lasher lattice model with a detailed investigation of samples containing 200 × 200 × 200 particles. The large-scale Monte Carlo (MC) simulations involved were carried out following the standard Metropolis, as well as the cluster MC Wolff algorithms. A notable free-energy barrier was observed between the isotropic and nematic phase, leading to long-lived metastable states and hysteresis.

Elastic constants and the formation of topological defects in hybrid nematic cells: A Monte Carlo study.

We present a Monte Carlo study of the effects of elastic anisotropy on the topological defects which can be formed in nematic films with hybrid boundary conditions. We simulate the polarized microscopy images and analyze their evolution in uniaxial systems for different values of the Frank elastic constants.

From Point to Filament Defects in Hybrid Nematic Films.

We have studied nematic hybrid films with homeotropic alignment at the top surface and various controlled degrees of in plane ordering, going from a random degenerate organization to a completely uniform alignment along one direction, at the bottom one. We show, by Monte Carlo (MC) computer simulations and experiments on photopatterned films with the bottom support surface fabricated with in-plane order similar to the simulated ones, that the point defects observed in the case of random planar orientations at the bottom tend to arrange along a filament as the surface ordering is sufficiently increased. MC simulations complement the polarized microscopy texture observations allowing to inspect the 3D structure of the defects and examine the role of elastic constants.