  This work discusses numerical studies of the barrier properties of k-mer
packings by Monte Carlo method. The studied variants of regular and non-regular
arrangements on a square lattice included models of random sequential
adsorption (RSA) and random deposition (RD). The discrete problem of diffusion
through the bonds of a square lattice was considered. The k-mers were perfectly
oriented perpendicular to the diffusion direction and blocked certain fraction
of bonds $f_b$ against diffusion. For loose RSA and RD packings, the
percolation like-behavior of diffusion coefficient was observed and the data
evidenced that their barrier properties at large values of k may be more
effective than those of some dense packings. Such anomalous behavior can
reflect the details of k-mer spatial organization (aggregation) and structure
of pores in RD and RSA packings. The contradictions between simulation data and
predictions of EM theory were also discussed.
