Critical Behavior of Long Straight Rigid Rods on Two-dimensional Lattices: Theory and Monte Carlo simulations

D. A. MATOZ-FERNANDEZ; D. H. LINARES; A. J. RAMIREZ-PASTOR

JOURNAL OF CHEMICAL PHYSICS

AMER INST PHYSICS

Año: 2008 vol. 128 p. 214902 - 214907

0021-9606

The critical behavior of long straight rigid rods of length k
k-mers on square and triangular lattices at intermediate density has been studied. A nematic phase, characterized by a big domain of parallel k-mers, was found. This ordered phase is separated from the isotropic state by a continuous transition occurring at an intermediate density
c. Two analytical techniques were combined with Monte Carlo simulations to predict the dependence of
c on k, being
c
kk−1. The first involves simple geometrical arguments, while the second is based on entropy considerations. Our analysis allowed us also to determine the minimum value of k
kmin=7, which allows the formation of a nematic phase on a triangular lattice.