SELF-AVOIDING WALK CONNECTIVITY CONSTANT AND THETA-POINT ON PERCOLATING LATTICES

The average connectivity constant mu of self-avoiding walks (SAWs) is obtained from exact enumeration of SAWs on Monte Carlo generated percolating clusters in a randomly diluted square lattice. For averages over the (infinite) percolating cluster, mu decreases almost linearly with bond dilution (1-p), where p is the bond occupation concentration. We find mu (p(c)) = 1.31 +/- 0.03 at the percolation threshold p(c) and could not detect any significant difference between mu(p(c)) and p(c)mu(1). The variation of theta-point for SAWs on the same lattice with dilution is also estimated, analysing the partition function zeros. Within the limited accuracy of our analysis, its variation with dilution is observed as being quite weak and the theta-point increases somewhat (compared to pure lattice value) near p(c); we find a non-vanishing theta-point (K-theta(p(c)) approximately equal 0.59, where K-theta = J/k-theta) on the square lattice percolation cluster at p(c).