Standard setup with two monolayers separated by a slab of water on one side and by a large vacuum space on the other side was used to simulate DPPC and POPC monolayers. The starting structures were taken from our previous work. The simulations were performed in the canonical ensemble (constant volume, temperature, and particle number) and with periodic boundary conditions in all directions. Monolayers were simulated at di↵erent areas per lipid to construct surface pressure-area isotherms that are readily comparable to experiments.