M. Jaric et al., VESICULAR INSTABILITIES - THE PROLATE-TO-OBLATE TRANSITION AND OTHER SHAPE INSTABILITIES OF FLUID BILAYER-MEMBRANES, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 52(6), 1995, pp. 6623-6634
The equilibrium shapes of fluid-phase phospholipid vesicles in an aque
ous solution are controlled by bending elasticity. The regime of nonve
siculated shapes at reduced volume v greater than or equal to 1/root 2
involves the interplay of five branches of distinct stationary shapes
: pears, prolates, oblates, stomatocytes, plus a branch of nonaxisymme
tric shapes with the symmetry D-2h. We exploit a method for calculatin
g explicitly the stability of arbitrary axisymmetric shapes to map out
in a numerically exact way both the stable phases and the metastabili
ty of the low-lying shape branches. To obtain additional required info
rmation about nonaxisymmetric shapes, we calculate these by numerical
minimization of the curvature energy on a triangulated surface. Combin
ing these two methods allows us to construct the full (shape) phase di
agram and the full stability diagram in this region. We provide explic
it results for values of the bending constants appropriate to stearoyl
-oleoyl-phosphatidylcholine; generalization to other values is straigh
tforward.