Gorkunov, M.V. and Osipov, Mikhail and Lagerwall, J.P.F. and Glesselmann, F. (2007) Order-disorder molecular model of the smectic- A–smectic-C phase transition in materials with conventional and anomalously weak layer contraction. Physical Review E, 76 (5).Full text not available in this repository. (Request a copy from the Strathclyde author)
We develop a molecular-statistical theory of the smectic-A–smectic-C transition which is described as a transition of the order-disorder type. The theory is based on a general expansion of the effective interaction potential and employs a complete set of orientational order parameters. All the order parameters of the smectic-C phase including the tilt angle are calculated numerically as functions of temperature for a number of systems which correspond to different transition scenario. The effective interaction potential and the parameters of the transition are also calculated for specific molecular models based on electrostatic and induction interaction between molecular dipoles. The theory successfully reproduces the main properties of both conventional and so-called “de Vries–type” smectic liquid crystals, clarifies the origin of the anomalously weak layer contraction and describes the tricritical behavior at the smectic-A–smectic-C transition. The “de Vries behavior,” i.e., anomalously weak layer contraction is also obtained for a particular molecular model based on interaction between longitudinal molecular dipoles. A simple phenomenological model is presented enabling one to obtain explicit expressions for the layer spacing and the tilt angle which are used to fit the experimental data for a number of materials.
|Keywords:||phase transition , liquid crystals, orientational order parameters , molecular dipoles, Probabilities. Mathematical statistics, Statistical and Nonlinear Physics, Statistics and Probability, Condensed Matter Physics|
|Subjects:||Science > Mathematics > Probabilities. Mathematical statistics|
|Department:||Faculty of Science > Mathematics and Statistics|
|Depositing user:||Pure Administrator|
|Date Deposited:||10 May 2011 14:07|
|Last modified:||27 May 2016 03:36|