Evolution of Topological Order in Xe Films on a Quasicrystal Surface

We report results of the first computer simulation studies of a physically adsorbed gas on a quasicrystalline surface Xe on decagonal Al-Ni-Co. The grand canonical Monte Carlo method is employed, using a semiempirical gas-surface interaction, based on conventional combining rules, and the usual Lennard-Jones Xe-Xe interaction. The resulting adsorption isotherms and calculated structures are consistent with the results of LEED experimental data. The evolution of the bulk film begins in the second layer, while the low coverage behavior is epitaxial. This transition from epitaxial fivefold to bulklike sixfold ordering is temperature dependent, occurring earlier (at lower coverage) for the higher temperatures.