Figure 15.

Upper leaflet tension ${\Sigma }_{ul}$ (blue) and lower leaflet tension ${\Sigma }_{ll}$ (red) versus lipid number $N_{ul}$ for constant total lipid number $N_{ul}+N_{ll}=1682$. The lipid number $N_{ul}$ is reduced by moving lipids from the upper to the lower leaflet, thereby increasing the upper leaflet tension and decreasing the lower one. Both leaflet tensions vanish for $N_{ul}=841$ (vertical dashed line) which defines the relaxed reference state of the planar bilayers. The green data display the bilayer tension $\Sigma ={\Sigma }_{ul}+{\Sigma }_{ll}$, which is close to zero, demonstrating that all bilayer states are OLT states. For $945\ge N_{ul}\ge 737$, the bilayer remains stable and the lipids do not undergo flip-flops from one leaflet to the other during the first 12.5 $\mathsf{\mu }$s of the simulations. The midplanes of the OLT states were obtained via the CHAIN protocol [30].