TY - JOUR

T1 - Energy surface and minimum energy paths for Fréedericksz transitions in bistable cholesteric liquid crystals

AU - Ivanov, A. V.

AU - Bessarab, P. F.

AU - Aksenova, E. V.

AU - Romanov, V. P.

AU - Uzdin, V. M.

N1 - Funding Information: This work was supported by Saint Petersburg State University (Grant No.11.37.145.2014), the Russian Foundation for Basic Research (Grant No. 14-02-00102), and the Nordic-Russian Training Network for Magnetic Nanotechnology (NCM-RU10121). P.B. gratefully acknowledges support from the Gran Gustafsson Foundation for Research in Natural Sciences and Medicine (Grant No. 1303A) Publisher Copyright: © 2016 American Physical Society. Copyright: Copyright 2017 Elsevier B.V., All rights reserved.

PY - 2016/4/27

Y1 - 2016/4/27

N2 - 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.

AB - 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.

KW - теория переходного состояния

KW - переход Фредерикса

KW - путь с наименьшим перепадом энергии

UR - http://www.scopus.com/inward/record.url?scp=84964598898&partnerID=8YFLogxK

U2 - 10.1103/PhysRevE.93.042708

DO - 10.1103/PhysRevE.93.042708

M3 - Article

VL - 93

JO - Physical Review E

JF - Physical Review E

SN - 1539-3755

IS - 4

M1 - 042708

ER -