POLYMER MODEL WITH ANNEALED DILUTION ON THE SQUARE LATTICE - A TRANSFER-MATRIX STUDY

We study a lattice model for equilibrium polymerization with annealed dilution. The model considered is an Ising lattice-gas monomer-solvent system where the polymers are represented by mutually and self-avoidi ng walks constrained to pass through sites occupied by monomers. Numer ical results on the square lattice using transfer-matrix techniques an d finite-size scaling are reported. The values obtained for the tricit ical exponent nu(t) are in agreement with the tricritical Ising expone nt (8/11) for high values of the monomer fugacity, but the accuracy we obtained does not rule out the possibility of nu(t) being equal to th e critical self-avoiding-walk (SAW) value 3/4. Our results indicate th at a crossover occurs in the tricritical behavior of the model. This c rossover corroborates the equivalence between a particular limit of th e diluted model and the self-attracting polymer system proposed recent ly.