Phase Diagram of Fluid Vesicles

The phase diagram of self-avoiding fluid vesicles as a function of the bending rigidity κ and the pressure increment p is studied using Monte Carlo simulations and scaling arguments. For $p>0$, a line of first-order transitions is observed between a branched-polymer-like phase and an inflated phase. The first-order line ends at small positive p; it extends to negative p as a line of compressibility maxima. For $p<0$, and sufficiently large κ, stomatocytes are stable. The scaling behavior as a function of system size is markedly different for positive and negative p.