title: Columnar phases of three-fold molecular structures.
abstract: We study the occurrence of both positional and helical orders, for three-fold symmetric flat molecules in a columnar liquid crystal phase D(hd). Working in the group-theoretical Landau's framework, we identify a set of three order parameters giving rise to supercells of intercalated column with helical order and opposite helicities, as observed experimentally. The first-order nature of the transition is also discussed. The degrees of freedom introduced give rise to various other phases, including a new type, having helical order but no positional order along the columns.
authors.affiliation: Département de Physique, Université de Montréal, Case Postale 6128, Succursale Centre-ville, Montréal, Quebec, Canada H3C 3J7.
authors.forename: Jean-Guy
authors.initials: JG
authors.lastname: Demers
authors.forename: Alain
authors.initials: A
authors.lastname: Caillé