Orientational dynamics in a liquid crystalline system near theisotropic-nematic (I-N) phase transition is studied using Molecular Dynamicssimulations of the well-known Lebwohl-Lasher (LL) model. As the I-N transitiontemperature is approached from the isotropic side, we find that the decay ofthe orientational time correlation functions (OTCF) slows down noticeably,giving rise to a power law decay at intermediate timescales. The angularvelocity time correlation function also exhibits a rather pronounced power lawdecay near the I-N boundary. In the mean squared angular displacement atcomparable timescales, we observe the emergence of a \emph{subdiffusive regime}which is followed by a \emph{superdiffusive regime} before the onset of thelong-time diffusive behavior. We observe signature of dynamical heterogeneitythrough \emph{pronounced non-Gaussian behavior in orientational motion}particularly at lower temperatures. This behavior closely resembles what isusually observed in supercooled liquids. We obtain the free energy as afunction of orientational order parameter by the use of transition matrix MonteCarlo method. The free energy surface is flat for the system considered hereand the barrier between isotropic and nematic phases is vanishingly small forthis weakly first-order phase transition, hence allowing large scale,collective and correlated orientational density fluctuations. This might beresponsible for the observed power law decay of the OTCFs.
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