Generalised interacting self-avoiding trails on the square lattice:   phase diagram and critical behaviour
  A generalised model for interacting self-avoiding trails on the square lattice is presented and studied using numerical transfer matrix methods. The model differentiates between on-site double visits corresponding to collisions, and crossings. Rigidity is also included in the model. The model includes the Nienhuis O(n=0) model and the interacting self-avoiding trail model as special cases. It is shown that the generic type of collapse found is the same as the pure interacting self-avoiding trail model. 
Damien P. Foster
cond-mat.stat-mech