TRANSITIONS TO ORDERED PHASES IN SYSTEMS CONTAINING ROD-LIKE PARTICLES .3. 4 FUNDAMENTAL REASONS FOR THE PREDICTIVE DEFICIENCIES OF DISCRETE LATTICE MODELS

This paper identifies and discusses four fundamental causes for the di screpancy between the entropy predictions of our new continuous-placem ent Monte Carlo (CMC) approach and the discrete lattice model (DLM) of Flory and Ronca. The DLM allows rods to cross, enables rods to fit to o easily into tight spaces, does not account for unoccupiable (wasted) space, and neglects the ingrowth of short-range order. Increasing res olution can eliminate the first two shortcomings from the DLM. To acco unt for wasted space in the DLM, it will be necessary to derive a more complex expression for combinatoric entropy. To properly accommodate the effect of short-range order, the calculation of both combinatoric and orientational entropy must be improved.