Research output: Contribution to journal › Article
First-order and continuous Fréedericksz transitions in cholesteric liquid crystals. / Val'Kov, A.Y.; Aksenova, E.V.; Romanov, V.P.
In: Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, Vol. 87, No. 2, 2013, p. 022508_1-13.Research output: Contribution to journal › Article
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TY - JOUR
T1 - First-order and continuous Fréedericksz transitions in cholesteric liquid crystals
AU - Val'Kov, A.Y.
AU - Aksenova, E.V.
AU - Romanov, V.P.
PY - 2013
Y1 - 2013
N2 - The Fréedericksz transition in twist cells of cholesteric liquid crystals with a finite surface energy is considered. It is shown that this transition can be either of the second order or of the first order depending on the values of the Frank constants, pitch, surface energies, and the cell thickness. A simple criterion that determines the order of the phase transition is obtained. By numerically minimizing the free energy of the liquid-crystal pattern the distribution of the director in the presence of the external electric field is calculated. For this purpose the polar angle of the director was presented as a partial sum of the Fourier series and of the appropriate function. The azimuthal angle was eliminated using Euler-Lagrange equations. Calculations were performed for different sets of liquid-crystal parameters which provide the phase transition of the first and of the second order. The numerical results are in a good agreement with theoretical formulas based on the Landau-type theory.
AB - The Fréedericksz transition in twist cells of cholesteric liquid crystals with a finite surface energy is considered. It is shown that this transition can be either of the second order or of the first order depending on the values of the Frank constants, pitch, surface energies, and the cell thickness. A simple criterion that determines the order of the phase transition is obtained. By numerically minimizing the free energy of the liquid-crystal pattern the distribution of the director in the presence of the external electric field is calculated. For this purpose the polar angle of the director was presented as a partial sum of the Fourier series and of the appropriate function. The azimuthal angle was eliminated using Euler-Lagrange equations. Calculations were performed for different sets of liquid-crystal parameters which provide the phase transition of the first and of the second order. The numerical results are in a good agreement with theoretical formulas based on the Landau-type theory.
KW - The Fréedericksz transition
KW - cholesteric liquid crystals
KW - vector director
KW - minimization
U2 - 10.1103/PhysRevE.87.022508
DO - 10.1103/PhysRevE.87.022508
M3 - Article
VL - 87
SP - 022508_1-13
JO - Physical Review E
JF - Physical Review E
SN - 1539-3755
IS - 2
ER -
ID: 7369589