  We present Monte Carlo simulations under constant NVT conditions on a minimal
three beads coarse grained implicit solvent model of lipid molecules, with the
hydrophilic head represented by one bead and the hydrophobic tail represented
by two beads. We consider two lipids, one with the head and tail bead sizes
equal and the other with the tail beads smaller than the head. When cooled to
the ambient temperature from an initial isotropic phase at high temperature,
the first lipid transforms spontaneously to a lamellar phase while the second
lipid transforms to a micellar phase, showing the crucial role of the head and
tail size ratio on lipid phases.
