Cesare Chiccoli

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Monte Carlo and theoretical studies of thin 3D films of biaxial and uniaxial nematics with tangential boundary conditions show distinct differences in structure and evolution of topological defects. In the uniaxial films, defects of strength k=+/-1 are point defects that bear no bulk singularity and disappear by annihilation with each other. In the biaxial(More)
Monte Carlo simulations of polarizing microscope textures for confined nematic droplets are presented. We consider uniaxial and biaxial cases with various boundary conditions and different values of the molecular biaxiality. The analysis of these optical textures should be of interest in assigning and characterizing biaxial nematic system, an issue of great(More)
We confirm by Monte Carlo simulations of a Lebwohl-Lasher lattice spin model the existence of a biaxially ordered nonbent structure in a liquid-crystalline cell subject to opposing boundary conditions. We report on the observation of the bending transition from the biaxial to the bent-director structure when the temperature of the system is lowered. The(More)
We present a combined experimental and Monte Carlo study of a nematic phase in the presence of quenched disorder. The turbidity of a nematic liquid crystal embedded in a porous polymer membrane is measured under different applied field conditions for field-cooled and zero-field-cooled samples. We find that a significant permanent alignment of the nematic(More)
The solution of many problems in radiative transfer and transport theory, requires calculations of real-order exponential integrals,E s (x). We consider a composite algorithm based on a recursive evaluation ofE s (x), $$s \in \mathbb{R}$$ ,x>0, starting from a suitable initial value in the region of positives andx arguments, which ensures the numerical(More)
A Monte Carlo simulation of a nematic Lebwohl-Lasher li uid crys-confined to a cylindrical pore is presented. We have calculated t ll e ordering and the molecular orgamsation inside the cavity for cylinders of different size when homeotropic radial boundar strengths are employed. We have not o iT conditions and different anchoring in the organisations(More)
The biaxial nematic phase diagram for the second rank Straley quadrupolar pair potential, as explored until now, implies that a direct transition from a biaxial nematic to an isotropic phase can occur, either at a single Landau point or even, as recently shown using mean field theory, along a line. We show by an extensive Monte Carlo investigation that a(More)
The orientational order in a nematic liquid crystal sample confined to an annular region between two concentric cylinders is investigated by means of lattice Monte Carlo simulations. Strong anchoring and homeotropic orientations, parallel to the radial direction, are implemented at the confining surfaces. The elastic anisotropy is taken into account in the(More)
Memory effects and glassy behavior have been repeatedly observed in disordered nematic liquid crystals but the connection between these effects and the system topology remained unrevealed. We present an analysis of the local and global topology of the nematic ordering in the presence of quenched disorder and we show that nematics with quenched disorder can(More)