Lawrence Livermore National Lab’s Biochemical and Biophysical Systems Group uses molecular dynamics simulations to study how lipid bilayers interact with drugs. The two leaflets of bilayers in real cells have different composition, but most simulations have used symmetric bilayers to avoid unrealistic stresses in the bilayer. Our project aims to develop a method to determine how many lipids to include in each leaflet of an asymmetric bilayer simulation to produce stress-free membranes.