The final configurations of the 4000 𝜏 long simulations of the S400 systems are provided. In Figure , the top views of the configurations are shown at different 𝑎 𝐿 , colored according to the tail order parameter ⟨𝑆⟩ = 1 2 (𝑆 𝑡𝑎𝑖𝑙 1 + 𝑆 𝑡𝑎𝑖𝑙 2 ), averaged over the two tails. The snapshots described in this way clearly show different monolayer phases containing lipids with definite tail orientations. At high compression (𝑎 𝐿 = 51. 𝐴 𝑜 2 ), the whole monolayer is in LC phases, with all lipids oriented along the bilayer normal (⟨𝑆⟩ ≈ 1). Domains of lower lipid order, representing the LE phase, appear and grow as the area per lipid increases, leading to LC-LE coexistence at intermediate values of 𝑎 𝐿 , and finally a complete LE phase. The LC phase is dominated by lipids with 𝑆 ≈ 1(red) while the LE phase is dominated with lipids that orient parallel to the interface (𝑆 ≈ -0.5, blue). In the monolayers with coexisting LE and LC phases, the LC and LE phases are separated by a region of 𝑆 ≈ 0.25 (green), which corresponds to a tail orientation 𝜃 = 45 0 .