Correlations in Interfaces with Surfactants

The existence or nonexistence of the bending coefficient in liquid interfaces, as well as the applicability of the Helfrich free energy, is examined by comparing correlations in the interfaces with or without a weak surfactant. In the latter case, the formation of a bilayer is studied and density–density correlations and height–height correlations are reported, analyzed, and compared with normal liquid interfaces. In particular, the role of lateral tension is discussed.