title: Energy surface and minimum energy paths for Fréedericksz transitions in bistable cholesteric liquid crystals.
abstract: The multidimensional energy surface of a cholesteric liquid crystal in a planar cell is investigated as a function of spherical coordinates determining the director orientation. Minima on the energy surface correspond to the stable states with particular director distribution. External electric and magnetic fields deform the energy surface and positions of minima. It can lead to the transitions between states, known as the Fréedericksz effect. Transitions can be continuous or discontinuous depending on parameters of the liquid crystal which determine an energy surface. In a case of discontinuous transition when a barrier between stable states is comparable with the thermal energy, the activation transitions may occur, and it leads to the modification of characteristics of the Fréedericksz effect with temperature without explicit temperature dependencies of liquid crystal parameters. A minimum energy path between stable states on the energy surface for the Fréedericksz transition is found using the geodesic nudged elastic band method. Knowledge of this path, which has maximal statistical weight among all other paths, gives the information about a barrier between stable states and configuration of director orientation during the transition. It also allows one to estimate the stability of states with respect to the thermal fluctuations and their lifetime when the system is close to the Fréedericksz transition.
authors.affiliation: Saint Petersburg State University, 199034, Saint Petersburg, Russia.|Science Institute of the University of Iceland, VR-III, 107 Reykjavik, Iceland.
authors.forename: A V
authors.initials: AV
authors.lastname: Ivanov
authors.affiliation: Saint Petersburg State University, 199034, Saint Petersburg, Russia.|Department of Materials and Nanophysics, Royal Institute of Technology (KTH), SE-16440 Kista, Sweden.
authors.forename: P F
authors.initials: PF
authors.lastname: Bessarab
authors.affiliation: Saint Petersburg State University, 199034, Saint Petersburg, Russia.
authors.forename: E V
authors.initials: EV
authors.lastname: Aksenova
authors.affiliation: Saint Petersburg State University, 199034, Saint Petersburg, Russia.
authors.forename: V P
authors.initials: VP
authors.lastname: Romanov
authors.affiliation: Saint Petersburg State University, 199034, Saint Petersburg, Russia.|Saint Petersburg National Research University of Information Technologies, Mechanics and Optics, 197101 Saint Petersburg, Russia.
authors.forename: V M
authors.initials: VM
authors.lastname: Uzdin