Molecular dynamics simulations of self-avoiding tethered membranes with attractive interactions: Search for a crumpled phase

The equilibrium structure of closed self-avoiding tethered vesicles with attractive interactions is investigated by molecular dynamics simulations. The vesicles are constructed by connecting linear chains of n=4 or 8 monomers to form closed membranes with as many as 16 002 monomers. For n=4, the transition from a high-temperature flat phase to a low-temperature collapsed phase is discontinuous, with no evidence for an intermediate crumpled phase. However, for n=8 the transition is either continuous or very weakly first order. Assuming the transition is continuous, a scaling analysis suggests that at the transition there is an intermediate state which has a fractal dimension df{}2.4, somewhat smaller than but close to the value predicted by the Flory theory for a crumpled membrane.