Hard rod and frustum model of two-dimensional vesicles

A two-dimensional vesicle of hard rods subject to a shadowing interaction is analyzed by Monte Carlo simulations. From the mode analysis of the shape fluctuation of the vesicle, the bending rigidity is estimated microscopically and the relation between the rod length and the bending rigidity is studied. A scaling relation of a mean square radius of gyration is investigated and compared with that proposed by Leibler, Singh and Fisher. Increasing osmotic pressure a vesicle performs a shape transition from a circular to bi-lobocyte shape. A vesicle with a spontaneous curvature is also studied by using molecules of a frustum shape