Calculation of long-range orientational order parameters in impure nematic liquid crystals using an extended van der Waals model

For the atended van der Waals model of a binary nematic system consisting of rigid biaxial molecules, we consider the following properties: the relation between the orientational order parameters of a nematic liquid crystal (NLC) S⁽¹⁾ and a nonmesomckphic impurity S⁽²⁾, the relation between S⁽²⁾ and the biaxiality parameter D⁽²⁾ of the impurity, and the lowered clearing temperature of NLC upon dissolution of the nonmesogen. The dependence of these characteristics on the fom and size of component molecules and the intermolecular attraction potential is analyzed. The model reproduces the experimental dependence of S⁽²⁾ and D⁽²⁾ on temperature and structure of the nematic matrix.Scientific Research Institute of Chemistry, St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 5, pp. 106–115, September–October, 1993.Translated by L. Smolina