title: Geometrically-controlled twist transitions in nematic cells.
abstract: We study geometrically controlled twist transitions of a nematic confined between a sinusoidal grating and a flat substrate. In these cells, the transition to the twisted state is driven by surface effects. We have identified the mechanisms responsible for the transition analytically and used exact numerical calculations to study the range of surface parameters where the twist instability occurs. Close to these values, the cell operates under minimal external fields or temperature variations.
authors.affiliation: Departamento de Física da Faculdade de Ciências and Centro de Física Teórica e Computacional, Universidade de Lisboa, Avenida Professor Gama Pinto 2, P-1649-003 Lisbon Codex, Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Patrício
authors.forename: M M
authors.initials: MM
authors.lastname: Telo da Gama
authors.forename: S
authors.initials: S
authors.lastname: Dietrich