title: Confinement of two-dimensional rods in slit pores and square cavities.
abstract: Using Monte Carlo simulation, we analyse the behaviour of two-dimensional hard rods in four different types of geometric confinement: (i) a slit pore where the particles are confined between two parallel walls with homeotropic anchoring; (ii) a hybrid slit pore formed by a planar and a homeotropic wall; square cavities that frustrate the orientational order by imposing either (iii) homeotropic or (iv) planar wall anchoring. We present results for the state diagram as a function of the packing fraction and the degree of confinement. Under extreme confinement, unexpected states appear with lower symmetries than those of the corresponding stable states in bulk, such as the formation of states that break the anchoring constraints or the symmetry imposed by the surfaces. In both types of square cavities, the particles form disclinations at intermediate densities. At high densities, however, the elastic stress is relaxed via the formation of domain walls where the director rotates abruptly by 90°.
authors.affiliation: Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Geigenfeind
authors.affiliation: Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Rosenzweig
authors.affiliation: Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Schmidt
authors.affiliation: Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: de Las Heras
mesh_terms: D003198:Computer Simulation; D050866:Liquid Crystals / Q000737:chemistry*; D008962:Models, Theoretical; D009010:Monte Carlo Method; D016062:Porosity; D013499:Surface Properties