PHASE-DIAGRAM AND SCALING BEHAVIOR OF FLUID VESICLES

The phase diagram and the scaling behavior of self-avoiding fluid vesicles as a function of the bending rigidity κ and the pressure increment Δp is studied using Monte Carlo simulations and scaling arguments. For Δp>0, a line of first-order transitions is observed between a branched-polymer-like phase and an inflated phase. The scaling behavior in the inflated phase along this line seems to be characterized by a universal exponent ν 0.8. The first-order line ends at small positive Δp; it extends to negative Δp as a line of compressibility maxima. For Δp<0, this line can be understood as a line of buckling transitions. For even more negative Δp and sufficiently large κ, stomatocytes are stable. We present evidence for the absence of a phase transition as a function of κ at Δp=0 by showing that the volume V of a N-monomer vesicle scales as V=N3/2ΘV(N /ξp), with a smooth scaling function ΘV. The exponent κ dependence of the persistence length ξp is found to be in excellent agreement with renormalization group results. © 1995 The American Physical Society.