Pressure-temperature phase diagrams of selenium and sulfur in terms of Patashinski model

The pressure - temperature phase diagrams of Se and S are calculated. Both melting and polymorphous phase transition are described in the frames of statistical Patashinski model. The results are in good agreement with experimental data of Brazhkin et. al.Comment: 3 eps figures, will appear in Physica A, mail to first author [email protected]

Liquid crystal hyperbolic metamaterial for wide-angle negative-positive refraction and reflection

We show that nanosphere dispersed liquid crystal (NDLC) metamaterial can be characterized in near IR spectral region as an indefinite medium whose real parts of effective ordinary and extraordinary permittivities are opposite in signs. Based on this fact we design a novel electrooptic effect: external electric field driven switch between normal refraction, negative refraction and reflection of TM incident electromagnetic wave from the boundary vacuum/NDLC. A detailed analysis of its functionality is given based on effective medium theory combined with a study of negative refraction in anisotropic metamaterials, and Finite Elements simulations

Cluster model of glass transition in simple liquids

On the basis of microscopic statistical mechanics of simple liquids the orientational interaction between clusters consisting of a particle and its nearest neighbors is estimated. It is shown that there are ranges of density and temperature where the interaction changes sign as a function of a radius of a cluster. The model of interacting cubic and icosahedral clusters is proposed and solved in mean-field replica symmetric approximation. It is shown that the glass order parameter grows smoothly upon cooling, the transition temperature being identified with the temperature of the replica symmetry breaking. It is shown that upon cooling a Lennard-Jones system, cubic clusters freeze first. The transition temperature for icosahedral clusters is about ten per cent lower. So the local structure of Lennard-Jones glass in the vicinity of glass transition should be most probably cubic.Comment: 4 pages, 3 figure

Monte Carlo study of tunable negative-zero-positive index of refraction in nanosphere dispersed liquid crystals

Khoo et al.1, 2 have shown that nanosphere dispersed nematic liquid crystal (NDLC) constitutes a new type of metamaterial with index of refraction tunable from negative to positive values. Recently3 we have combined this approach with Monte Carlo simulations of inhomogeneous molecular order in planar NLC cells. Lebwohl - Lasher effective hamiltonian with Rapini - Papoular term for anchoring forces was used. Electric field and amplitude of anchoring forces are control parameters which determine the profiles of order parameter. In this paper we study, using the same approach, local spatial distribution of refractive index in NDLC planar cell. We show that NDLC material consists of layers with negative-zero-positive index of refraction. The spatial organization of those layers strongly depends on incident light wavelength. The role of spatially modulated external electric field for tuning of refractive index of NDLC is briefly discussed

Short-time dynamics of the positional order of the two-dimensional hard disk system

We investigate the positional order of the two-dimensional hard disk model with short-time dynamics and equilibrium simulations. The melting density and the critical exponents z and eta are determined. Our results rule out a phase transition as predicted by the Kosterlitz-Thouless-Halperin-Nelson-Young theory as well as a first-order transition.Comment: 8 pages, 4 figures, minor change

The hexatic phase of the two-dimensional hard disks system

We report Monte Carlo results for the two-dimensional hard disk system in the transition region. Simulations were performed in the NVT ensemble with up to 1024^2 disks. The scaling behaviour of the positional and bond-orientational order parameter as well as the positional correlation length prove the existence of a hexatic phase as predicted by the Kosterlitz-Thouless-Halperin-Nelson-Young theory. The analysis of the pressure shows that this phase is outside a possible first-order transition.Comment: 6 pages, 4 figures (minor changes