Transitions to Ordered Phases in Systems Containing Rodlike Particles: I. A New Continuum Monte Carlo Approach

Abstract

A new continuous-placement Monte Carlo (CMC) approach was developed that 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 configurations represent equilibrium conditions. Rod concentrations, orientation distribution shapes, and order parameters that are expected to be present at equilibrium can then be determined by comparing free energy curves. The method was applied to two-dimensional, monodisperse, athermal systems and the results demonstrated that choice of the shape of the global orientation distribution in the anisotropic phase can result in shifting from a first-order to a continuous isotropic-to-nematic phase transition.

Key Words:

• athermal
• axial ratio
• combinatoric entropy
• Monte Carlo
• orientational entropy
• rodlike particles