Figure 2.
Mathematical representation of the membrane. A. A cartoon model representing the upper and lower leaflets and the corresponding lipid molecules. N⃗ is the normal vector of the bilayer midplane (dashed line), n⃗ is the head-to-tail vector of the lipids, and t⃗ is the difference of these two vectors. B. The upper and lower surfaces representing the head-group interfaces with the water from panel A (solid lines) and the bilayer midplane (dashed line). The lipids have been removed in this purely mathematical representation, but the vectorial descriptions N⃗± and n⃗± remain.