First-order transition of a compartmentalized surface model for fluid membranes

Dynamically triangulated surface model is found to undergo a first-order crumpling transition between the smooth phase and a crumpled phase. Triangulated spheres are divided into compartmentalized domains, whose boundary bonds remain unflipped in the Monte Carlo simulations. The vertices can freely diffuse only inside the compartments, and they are prohibited from the free diffusion over the surface due to the domain boundaries. The violation of reparametrization invariance of the Hamiltonian is a reason for the existence of the long-range order in the fluid surface model.