Polymers with attractive interactions on the Husimi lattice

P. SERRA, J.F. STILCK, K.D. MACHADO Y W.L. CAVALCANTI

JOURNAL OF PHYSICS. A - MATHEMATICAL AND GENERAL

Institute of Physics

Año: 2004 vol. 37 p. 8811 - 8821

0305-4470

We obtain the solution of models of self-avoiding walks with attractiveinteractions on Husimi lattices built with squares. Two attractive interactionsare considered: between monomers on first-neighbour sites and not consecutivealong a walk and between bonds located on opposite edges of elementarysquares. For coordination numbers q > 4, two phases, one polymerized, theother non-polymerized, are present in the phase diagram. For small values ofthe attractive interaction the transition between those phases is continuous, but for higher values a first-order transition is found. Both regimes are separated by a tricritical point. For q = 4 a richer phase diagram is found, with an additional (dense) polymerized phase, which is stable for sufficiently strong interactions between bonds. The phase diagram of the model in the threedimensionalparameter space displays surfaces of continuous and discontinuousphase transitions and lines of tricritical points, critical endpoints and triple points.