Monte Carlo study of systems of linear oligomers in two-dimensional spaces

Abstract

The statistical mechanical properties of systems of linear r-mers (r=4, 5, and 6) in a square lattice space and of those in a two-dimensional continuous space were studied by Monte Carlo simulations. In the lattice space systems, the site fractions of the 4-mers ranged from 0.08 to 0.75, those of the 5-mers from 0.075 to 0.800, and those of the 6-mers from 0.12 to 0.667. In the continuous space systems, the concentrations were in more narrow ranges. In the lattice space systems, statistical quantities of finite systems were extrapolated to those of infinite systems. Pressures or osmotic pressures of the lattice space systems were close to the Huggins and the Miller–Guggenheim theoretical ones, while pressures of the continuous space systems, in dilute concentrations ranges, were better described by the Flory theory. The occurrence of each conformation of the r-mers was random in dilute concentration ranges but not in dense ranges. The nonrandomness was much increased in the continuous space systems, especially in the case of the 4-mers. No sign of the cooperative aligning of the r-mers was found in the lattice space systems.