  We present Monte Carlo simulations of a coarse-grained model for Langmuir
monolayers of amphiphile molecules on a polar substrate. The molecules are
modelled as chains of Lennard-Jones beads, with one slightly larger end bead
confined in a planar surface. They are simulated in continuous space under
conditions of constant pressure, using a simulation box of variable size and
shape. The model exhibits a disordered phase (corresponding to the liquid
expanded phase), and various ordered phases (corresponding to the condensed
phases) with different types of tilt. We calculate the phase diagrams and
characterize the different phases and phase transitions. The effect of varying
the chain stiffness is also discussed.
