6533b82afe1ef96bd128b888

RESEARCH PRODUCT

Competition between submonolayer ordering and multilayer adsorption: Studies of simple lattice gas models

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Abstract We model condensation of adatoms at a substrate surface by a semi-infinite simple cubic lattice gas system. While in the bulk there is just a nearest-neighbour attractive interaction, in the first layer adjacent to the surface we allow for a periodic potential due to the substrate with a period of two lattice spacings, or for a next-nearest-neighbour repulsive interaction mediated by the substrate. Hence order-disorder phenomena may occur in the first layer, while only gas-liquid condensation transitions can occur in layers further away from the substrate surface. The ground-state phase diagrams of this model are obtained exactly, while the behaviour at nonzero temperatures is obtained approximately via mean-field and Monte Carlo calculations. Particular attention is paid to the influence of these order-disorder phenomena in the first layer on the condensation transition of the second layer. We briefly compare our findings to related work and discuss possible experimental applications.