COMPUTER-SIMULATION OF A HARD-ROD SYSTEM - STRUCTURAL TRANSITIONS ANDCLUSTERS

We have studied by computer simulation a continual 2D hard-rod system with volume topological interaction between the rods. The microstructu re of the rods that is obtained can be conveniently analyzed with the help of cluster formation terminology. We have shown that cluster dist ribution with respect to the numbers of rods can be written as P(N) = A0 exp[(A1)N], where A0 and A1 are constants which depend upon the clu ster forming criteria and the rod system density, rho, and N is the nu mber of rods in a cluster. There are two transition regions in the har d-rod system of 2D spherocylinders at the axes ratio p = 6. The transi tion at rho = 0.35-0.40 is the structural transition from the intermed iate solution of rods and clusters to the solution of overlapped rods and clusters. The transition at rho = 0.50-0.55 can be associated with the appearance in the system of percolation clustering. The cluster i n the 2D rod system can therefore be considered to be a quasi-rod. The implication of this is that thermodynamic calculations for the system should be carried out as they would be for a polydisperse system with a given distribution of quasi-rods.