Entropy of Rodlike Particles: Continuum versus Lattice Representations

Abstract

The computationally tractable discrete lattice model is compared to a more realistic representation of rodlike particles, which allows continuous variation of rod position and orientation. This continuous-placement Monte Carlo method provides a measurement of the combinatoric entropy of rod configurations. Comparisons reveal that the discrete lattice model overestimates the entropy of short rods and of disordered phases. Three fundamental reasons for these predictive errors are discussed.

Key Words:

• axial ratio
• combinatoric entropy
• discrete lattice model
• Monte Carlo
• orientational entropy
• rodlike particles