Fluctuation-induced aggregation of rigid membrane inclusions

The phase behavior of fluid membranes containing inclusions with increased elastic moduli is studied by analytical methods and Monte Carlo simulations. We consider i) inclusions with larger bending rigidity which restrict fluctuations of the mean curvature and ii) "stiff" inclusions suppressing fluctuations of both mean curvature and Gaussian curvature at the inclusion sites. Due to the suppression of membrane fluctuations, the aggregation of inclusions with larger bending rigidity is already observed for relatively weak mutual direct interactions. In the case of sti inclusions, a strong fluctuation-induced tendency to aggregate is found even in the absence of direct interactions between the inclusions.