From percolating to dense random stick networks: Conductivity model investigation

In a Monte Carlo study the conductivity of two-dimensional random stick systems is investigated from the percolation threshold up to ten times the percolation threshold density. We propose a model explicitly depending on the stick density and junction-to-stick conductance ratio. The model describes the transition from the conductivity determined by the structure of a percolating cluster to the conductivity of the dense random stick networks. The model is motivated by the observed densities of the sticks and contacts involved in the current flow. The finite-size scaling effects are also included in the description. The derived model for conductivity should be broadly applicable to the random networks of the rodlike particles.