Balance of forces in simulated bilayers

Abstract

Two kinds of simulated bilayers are described and the results are reported for lateral tension and for partial contributions of intermolecular forces to it.Data for a widest possible range of areas per surfactant head, from tunnel formation through tensionless state, transition to floppy bilayer,to its disintegration, are reported and discussed. The significance of the tensionless state, is discussed. Conclusions: (1) the tensionless state is a coincidence;(2) the transition from extended to floppy bilayer occurs nearby and has hallmarks of a phase transition (3) there is no theory of that transition.(4)The lateral tension of the floppy bilayer scales with size; that of the extended bilayer does not depend on size. (4) The drumhead model not appropriate for interfaces as these fluctuate via diffusion.(5) The radius of gyration also! shows a discontinuity.