It is shown that a quartic orientational free energy leads to long-range icosahedral bond-orientational order which, through a coupling with a translational order parameter, stabilizes the icosahedral quasicrystalline phase. The bond-orientational order selects the wave vectors which point into vertices or faces of an icosahedron.

• Received 23 April 1985

DOI:https://doi.org/10.1103/PhysRevLett.55.607