J. Phys. I France
Volume 4, Numéro 8, August 1994
Page(s) 1139 - 1149
DOI: 10.1051/jp1:1994244
J. Phys. I France 4 (1994) 1139-1149

Monte Carlo study of the inflation-deflation transition in a fluid membrane

B. Dammann1, H. C. Fogedby2, J. H. Ipsen1 and C. Jeppesen3

1  Department of Physical Chemistry, The Technical University of Denmark, DK-2800 Lyngby, Denmark
2  Institute of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark
3  Materials Research Laboratory, University of California, Santa Barbara, CA 93106, U.S.A.

(Received 22 February 1994, accepted 15 April 1994)

We study the conformation and scaling properties of a self-avoiding fluid membrane, subject to an osmotic pressure p, by means of Monte Carlo simulations. Using finite size scaling methods in combination with a histogram reweighting techniques we find that the surface undergoes an abrupt conformational transition at a critical pressure $p^{\ast}$, from low pressure deflated configurations with a branched polymer characteristics to a high pressure inflated phase, in agreement with previous findings [1, 2]. The transition pressure $p^{\ast}$ scales with the system size as $p^{\ast} \propto N^{- \alpha}$, with $\alpha =
0.69 \pm 0.01$ . Below $p^{\ast}$ the enclosed volume scales as $V \propto N$, in accordance with the self-avoiding branched polymer structure, and for $p \searrow p^{\ast}$ our data are consistent with the finite size scaling form $V \propto N^{\beta_{+}}$, where $\beta_{+} =
1.43 \pm 0.04$ . Also the finite size scaling behavior of the radii of gyration and the compressibility moduli are obtained. Some of the observed exponents and the mechanism behind the conformational collapse are interpreted in terms of a Flory theory.

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