3d Monte Carlo simulation of site-bond continuum percolation of spheres.

We present off-lattice Monte Carlo simulations of site-bond percolation of semi-penetrable spheres or, equivalently, of hard spheres with a finite bond range. We will show that the crucial parameter is the effective volume fraction (phie), i.e. the volume that is occupied or within the bond range of at least one particle. For the equivalent system of semi-penetrable spheres 1-phie is the porosity. The bond percolation threshold (pb) can be described in terms of phie by a simple analytical expression: log(phie)/log(phiec) + log(pb)/log(pbc)=1, with pbc=0.12 independent of the bond range and phiec a constant that decreases with increasing bond range.