On Theory of Order Parameters in (Nematic) Liquid Crystals Beyond Homogeneous Molecular Field Approximation

Abstract

In this work there is presented a general theory of order parameters in liquid crystals beyond the homogeneous molecular field approximation, inclusive a new formula for C_v , and discussed in relation with Monte-Carlo based theories. There is shown that those two theoretical schemes are to some extend complementary. Numerical results for the temperature dependences of the average order parameter, “local order parameters” of individual molecules and C_v of a nematic with several different degrees of disorder are also deliberated.

The theory is then applied to the case of molecules of dyes in a nematic host in which the order parameter of the dye differs considerably relative to the order parameters of the host. Numerical results are given for several arrangements of the liquid crystal structure and discussed in relations with published experimental data. It is shown that by such an analysis there can be gained new information about the interatomic potentials.

Key Words:

• disorder
• average and local order parameters
• specific heat
• anthraquinone dyes