Low-temperature phases of Xe on graphite

Light and superlight wall energies for a xenon monolayer on graphite are calculated by a classical, zero-temperature relaxation scheme. Phase diagrams are then obtained using a striped helical Potts model for domain wall networks (such as striped or hexagonal incommensurate solids). The commensurate-incommensurate transition noted in past electron diffraction experiments is reinterpreted as a structural transition between two incommensurate solids, in agreement with recent x-ray scattering work. Matching experimental transition lines lead to estimates for various interatomic potentials. We discuss the preemption of the incipient commensurate phase by condensation of the bilayer.