TRANSITIONS TO ORDERED PHASES IN SYSTEMS CONTAINING RODLIKE PARTICLES.1. A NEW CONTINUUM MONTE-CARLO APPROACH

A new continuous-placement Monte Carlo (CMC) approach was developed th at measures the entropy of rodlike particle configurations having pre- set global orientation distributions. Entropies are measured through a range of concentrations, independently of whether these configuration s represent equilibrium conditions. Rod concentrations, orientation di stribution shapes, and order parameters that are expected to be presen t at equilibrium can then be determined by comparing free energy curve s. The method was applied to two-dimensional, monodisperse, athermal s ystems and the results demonstrated that choice of the shape of the gl obal orientation distribution in the anisotropic phase can result in s hifting from a first-order to a continuous isotropic-to-nematic phase transition.