CRITICAL-BEHAVIOR OF UNIAXIAL-BIAXIAL NEMATIC PHASE-TRANSITION

A model considering both rodlike molecules and platelike molecules is presented in this paper. The model is treated in the framework of a La ndau mean-field theory and renormalization group theory. Mean-field th eory predicts the transition between the isotropic, rod nematic, plate nematic, and biaxial nematic phases. The renormalization group analys is shows that the transition exhibits a multiphase bicritical point fo r n (dimensionality of the order parameter) less than or equal to 2. H owever, for n > 2, the transition exhibits a tetracritical point and a n intermediate biaxial nematic phase can exist. The critical exponents are calculated to first order in epsilon (=4-d). (C) 1998 American In stitute of Physics.