The bending rigidity κ of bilayer membranes was studied with coarse grained soft repulsive potentials using dissipative particle dynamics (DPD) simulations. Using a modified Andersen barostat to maintain the bilayers in a tensionless state, the bending rigidity was obtained from a Fourier analysis of the height fluctuations. From simulations carried out over a wide range of membrane thickness, the continuum scaling relation κ ∝ d2 was captured for both the Lα and Lβ phases. For membranes with 4 to 6 tail beads, the bending rigidity in the Lβ phase was found to be 10–15 times higher than that observed for the Lα phase. From the quadratic scalings obtained, a six fold increase in the area stretch modulus, kA was observed across the transition. The magnitude of increase in both κ and kA from the Lα to the Lβ phase is consistent with current experimental observations in lipid bilayers and to our knowledge provides for the first time a direct evaluation of the mechanical properties in the Lβ phase.
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