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 {Δ}p is studied using Monte Carlo simulations and scaling arguments. For {Δ}p>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 {Δ}p; it extends to negative {Δ}p as a line of compressibility maxima. For {Δ}p0, this line can be understood as a line of buckling transitions. For even more negative {Δ}p and sufficiently large {κ}, stomatocytes are stable. We present evidence for the absence of a phase transition as a function of {κ} at {Δ}p=0 by showing that the volume V of a N-monomer vesicle scales as 〈V〉=N3/2{{{Θ}}}V(N /{{ξ}}ₚ$), with a smooth scaling function ${{{Θ}}}V. The exponent κ dependence of the persistence length{{ξ}}ₚ$ is found to be in excellent agreement with renormalization group results.