Four-armed starfish in two lipid bilayer models

Summary In Helfrich spontaneous curvature model (HSC) the energy functional to be minimized for equilibrium shapes is $E_H=\int{(H-H_0)^2} da$, under constraints of fixed volume and fixed area, where $H$ is the local mean curvature and $H_0$ is the spontaneous curvature parameter. Here we report an experiment that, by adjusting $H_0$ one may yield a qualitatively similar equilibrium shape to the bilayer couple model (BC). In BC, energy is $W=\int{H^2}da$ (see Ziherl & Svetina, 2005) with mean curvature integral $c=\int{H da}/4\pi$ fixed ( $c=c_0$ )as a third constraint (the reference shape is the unit sphere with area $4\pi$ and $H=1$). This record includes datasets/ procedures for the open software Surface Evolver. ERRATUM: $H_0=2 c_0$ is not generaizable, see updated version.