Interacting elastic lattice polymers: a study of the free energy of globular rings.

We introduce and implement a Monte Carlo scheme to study the equilibrium statistics of polymers in the globular phase. It is based on a model of "interacting elastic lattice polymers" and allows a sufficiently good sampling of long and compact configurations, an essential prerequisite to study the scaling behavior of free energies. By simulating interacting self-avoiding rings at several temperatures in the collapsed phase, we estimate both the bulk and the surface free energy. Moreover from the corresponding estimate of the entropic exponent α-2 we provide evidence that, unlike for swollen and Θ-point rings, the hyperscaling relation is not satisfied for globular rings.