Universal Ratio χ in Two-Dimensional Square Random-Site Percolation

The percolation phenomena on two-dimensional square lattice is considered. The quotient χ of connectivity length ξ^> above percolation threshold p_c and ξ^< below p_c at the same small distance Δp is discussed. The results of two different algorithms and programs and agreement with theoretical/mathematical predications is presented, in contrast to previous contradictory Monte Carlo simulation results.