MONTE-CARLO STUDY OF THE INFLATION-DEFLATION TRANSITION IN A FLUID MEMBRANE

We study the conformation and scaling properties of a self-avoiding fl uid membrane, subject to an osmotic pressure p, by means of Monte Carl o simulations. Using finite size scaling methods in combination with a histogram reweighting techniques we find that the surface undergoes a n abrupt conformational transition at a critical pressure p, from low pressure deflated configurations with a branched polymer characterist ics to a high pressure inflated phase, in agreement with previous find ings [1, 2]. The transition pressure p scales with the system size as p is-proportional-to N(-alpha), with alpha = 0.69 +/- 0.01. Below p* the enclosed volume scales as V is-proportional-to N, in accordance w ith the self-avoiding branched polymer structure, and for p arrow poin ting down and to the right p our data are consistent with the finite size scaling form V is-proportional-to N(beta+), where beta+ = 1.43 +/ - 0.04. Also the finite size scaling behavior of the radii of gyration and the compressibility moduli are obtained. Some of the observed exp onents and the mechanism behind the conformational collapse are interp reted in terms of a Flory theory.