Director dynamics near the nematic-smectic-A phase transition |
| |
Authors: | S V Ul’yanov |
| |
Institution: | (1) St. Petersburg Institute of Trade and Economics, 194018 St. Petersburg, Russia |
| |
Abstract: | The Landau-de Gennes model for the free energy of a nematic liquid crystal near the phase transition to the smectic A-phase is used to determine the frequency dependence of the fluctuation corrections to the Frank elastic constants. It is
shown that the interaction of the fluctuations of the smectic order parameter and the director results in corrections to all
the Frank elastic constants. In the low-frequency limit (ω→0), the corrections to the Frank elastic constants K
22 and K
33 are the largest, and decrease to zero in the infinite-frequency limit. The correction to K
11 is negative, and vanishes in both limits. The absolute value of the correction to K
11 is the largest at frequencies in the megahertz range. It is shown that in oriented nematics the interaction of the smectic
fluctuations and the director limits deviations of the director from the direction of preferred orientation, as a result of
which relaxation of both inhomogeneous and homogeneous distortions of the director field can be observed. It is also shown
that this gives rise to a frequency interval in the megahertz range in which shear waves begin to propagate in the nematic.
The propagation speed of these waves is roughly a hundred times smaller than that of sound and strongly depends on the direction
of propagation.
Zh. éksp. Teor. Fiz. 114, 2022–2033 (December 1998) |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|